JP7626935B2 - Dust generation rate estimation device and dust generation rate estimation method - Google Patents

Description

This disclosure relates to a dust generation rate estimation device and a dust generation rate estimation method.

The molten iron obtained from the blast furnace is refined in a converter. In the refining process in the converter, processes such as decarburization and desiliconization are carried out, and the height of the main lance, the oxygen supply rate, the amount of auxiliary materials added, etc. are controlled according to the progress of these processes. In controlling such converters, a technology that utilizes the emission spectrum of the converter combustion flame has been known for some time.

Patent documents 1 and 2 disclose a method for analyzing converter exhaust gas in which light emission is analyzed in the converter exhaust gas flue and the component concentrations of the exhaust gas and dust in the flue are calculated in order to estimate decarburization and other processes during the refining process with high accuracy.

Patent Document 3 discloses a spectroscopic characteristic measuring device that includes an imaging spectroscopic device that acquires the light emitted by an object as spectroscopic information, a two-dimensional imaging device that captures an image of a two-dimensional area of the object, and a calculation device that determines the range from which the imaging spectroscopic device acquires spectroscopic information based on the image captured by the two-dimensional imaging device. Patent Document 3 also describes using this technology to measure the spectroscopic characteristics of a flame generated from a refining furnace and to control the refining furnace.

Patent documents 4 and 5 disclose a technique for measuring the emission spectrum of the furnace-mouth combustion flame blowing out from the furnace mouth of a converter, calculating the change over time in emission intensity at wavelengths in the measured range of 580 to 620 nm, estimating changes in conditions inside the furnace based on the calculated changes over time in emission intensity, and estimating the end point of the desiliconization reaction and the carbon concentration of molten iron based on the estimated changes in conditions inside the furnace.

Patent Document 6 discloses a technique for estimating the carbon concentration in molten metal based on performance information, including information about the optical characteristics of the throat of a converter.

Japanese Patent Application Laid-open No. 62-90524 Japanese Unexamined Patent Publication No. 62-90525 International Publication No. 2019/168141 JP 2020-105610 A JP 2020-105611 A WO 2019/220800

Incidentally, the amount of dust generated during converter blowing amounts to 1% to several percent of the total molten iron, so reducing the amount of dust generated during converter operation directly leads to cost reduction. However, the dust generation rate estimation methods proposed so far have involved manually sampling the dust amount or continuously measuring the dust amount using dust collection water or exhaust gas piping, and required maintenance including periodic replacement of parts and removal and cleaning of parts in areas that are infrequently visited during normal operation. For this reason, it was difficult to constantly carry out such a labor-intensive method in a converter that is constantly in operation. Furthermore, the techniques in Patent Documents 1 to 6 were not designed to estimate the dust amount (dust generation rate).

In view of the above, the objective of the present disclosure is to provide a dust generation rate estimation device and a dust generation rate estimation method that can operate continuously, have a small maintenance load, and estimate the dust generation rate with high accuracy.

The present disclosure provides, as one means for solving the above problem, an apparatus for estimating the generation rate of dust generated during the operation of a refining furnace, which includes a combustion flame generated at the opening of the refining furnace, and includes a spectral radiance acquisition unit that sets a plurality of optical paths of different lengths, and acquires the spectral radiance of the radiation spectrum at a wavelength of interest in each of the optical paths for each optical path, a combustion flame temperature estimation unit that estimates the temperature of the combustion flame at the time the spectral radiance acquisition unit acquires the spectral radiance for each optical path, and a blackbody radiance of the wavelength of interest at the estimated combustion flame temperature is calculated based on the optical path. The dust generation speed estimation device includes a blackbody radiation luminance calculation unit that calculates the spectral emissivity for each optical path from the ratio of the spectral luminance acquired by the spectral luminance measurement unit and the blackbody radiance calculated by the blackbody radiation luminance calculation unit, a spectral emissivity ratio calculation unit that selects two of the calculated spectral emissivities and calculates the spectral emissivity ratio, which is the ratio between them, and a dust generation speed estimation unit that estimates the dust generation speed based on a relational equation between the spectral emissivity ratio and the dust generation speed that has been obtained in advance.

In the above dust generation rate estimation device, the optical path may include an optical path that includes the lance of the refining furnace on the extension line of the optical path, and an optical path that does not include the lance of the refining furnace on the extension line of the optical path.

As one means for solving the above problem, the present disclosure provides a refining furnace that controls the refining furnace based on the dust generation rate estimated by the above dust generation rate estimation device.

The present disclosure provides, as one means for solving the above problem, a method for estimating the generation rate of dust generated during the operation of a refining furnace, which includes a combustion flame generated at the opening of the refining furnace, and includes a spectral radiance acquisition process for setting a plurality of optical paths of different lengths, and acquiring the spectral radiance of the radiation spectrum at a wavelength of interest in each optical path, a combustion flame temperature estimation process for estimating, for each optical path, the temperature of the combustion flame when the spectral radiance was acquired in the spectral radiance acquisition process, and a blackbody radiance of the wavelength of interest at the estimated combustion flame temperature, for each optical path. The method includes a blackbody radiation luminance calculation step of calculating the spectral emissivity for each optical path from the ratio of the spectral luminance acquired in the spectral luminance measurement step and the blackbody radiance calculated in the blackbody radiation luminance calculation step, a spectral emissivity ratio calculation step of selecting two of the calculated spectral emissivities and calculating the spectral emissivity ratio, which is the ratio between them, and a dust generation rate estimation step of estimating the dust generation rate based on a relational expression between the spectral emissivity ratio and the dust generation rate that has been obtained in advance.

In the above dust generation rate estimation method, the light path may include a light path that includes the lance of the refining furnace on the extension line of the light path, and a light path that does not include the lance of the refining furnace on the extension line of the light path.

As one means for solving the above problem, the present disclosure provides a method for controlling a refining furnace, which controls the refining furnace based on the dust generation rate estimated by the above dust generation rate estimation method.

According to the present disclosure, continuous operation is possible, the maintenance load is small, and the dust generation rate can be estimated with high accuracy.

FIG. 1 is a schematic diagram of a dust generation rate estimation device 100. FIG. 2 is a diagram for explaining optical paths (1) to (3) in the first embodiment. 1 shows the relationship between the spectral emissivity ratio and the amount of filter collected per unit time in Example 1. 11 is a diagram showing a relationship between the filter collection amount per unit time estimated from the spectral emissivity ratio in Example 1 and the actual filter collection amount per unit time. 13 shows the relationship between the spectral emissivity ratio and the actually measured dust generation rate (index value) and the elapsed time in Example 2.

The inventors of the present invention measured the combustion flame generated at the opening (furnace port frame) of the refining furnace with a spectroscope and confirmed that the radiation spectrum was the main component. The spectral emissivity can be calculated from the ratio of the measured luminance at the wavelength of interest of this radiation spectrum to the blackbody radiance calculated by Planck's law. If no luminous material is included in the measurement area, the measured value of the spectral emissivity is 0, while if the measurement area is seemingly filled with luminous materials, it is equivalent to surface emission, and the measured value of the spectral emissivity coincides with the spectral emissivity as a property of the luminous material. In this way, since the measured spectral emissivity depends on the concentration of the luminous material (dust in the case of the furnace port combustion flame) in the measurement area, the inventors of the present invention came up with the idea that the generation rate of dust in the refining furnace can be estimated based on the spectral emissivity. To confirm the success of this idea, the inventors used a test converter to evaluate the relationship between the spectral emissivity calculated from the radiation spectrum of the combustion flame and the amount of dust generated collected from a filter, and confirmed that there was a good correlation between the spectral emissivity and the amount of dust generated.

On the other hand, we also found that it is difficult to eliminate factors that affect the measurement results of spectral radiance when estimating dust generation rate based on spectral emissivity. For example, (A) the effect on spectral emissivity of the type of particles that make up the dust and their surface condition, (B) the effect of dust and water vapor floating on the light path (from the focusing part to the furnace opening), and (C) the effect of correction factors of the optical system (lens transmittance and optical fiber characteristics).

The inventors have discovered that by taking the ratio of the spectral emissivity obtained from multiple measurement points with different effective optical path lengths, it is possible to eliminate these effects and improve the estimation accuracy. The dust generation rate estimation device and dust generation rate estimation method disclosed herein were invented based on this discovery. Below, the dust generation rate estimation device and dust generation rate estimation method disclosed herein will each be described.

[Dust generation rate evaluation device]
The dust generation rate evaluation device of the present disclosure will be described using a dust generation rate evaluation device 100 (hereinafter, sometimes referred to as "device 100") as one embodiment. A schematic diagram of the device 100 is shown in FIG.

The device 100 is a device that estimates the dust generation rate generated during the operation of the refining furnace 1, and includes a spectral radiance acquisition unit 10 and a calculation unit 20 that performs calculations to estimate the dust generation rate.

The spectral radiance acquisition unit 10 includes a combustion flame generated at the opening 2 of the refining furnace 1, and sets multiple light paths of different lengths to acquire the spectral radiance of the radiation spectrum at the wavelength of interest for each light path. The number of light paths set may be only two.

The spectral radiance acquisition unit 10 includes a light acquisition unit 11 and a spectrometer 12, and the light acquisition unit 11 and the spectrometer 12 are connected by an optical fiber or the like. Such a spectral radiance acquisition unit 10 has a known configuration.

The spectral radiance acquisition unit 10 may include a plurality of light acquisition units 11 and spectrometers 12 since it acquires the spectral radiance of the radiation spectrum at the wavelength of interest from a plurality of light paths with different optical path lengths. FIG. 1 shows the spectral radiance acquisition unit 10 including two light acquisition units 11 and two spectrometers 12. This allows the spectral radiance of the wavelength of interest for each light path to be measured simultaneously. On the other hand, when there is only one light acquisition unit 11 and one spectrometer 12, the spectral radiance is measured sequentially for each light path, but the measurement interval needs to be as short as possible. For example, within 10 seconds. Methods for measuring the spectral radiance sequentially include a method of mechanically or electronically switching between a plurality of light paths, and a method of measuring by moving the spectral radiance acquisition unit 10 (or the light acquisition unit 11) using a stage.

The light acquisition unit 11 only needs to be positioned in a position where it can acquire the light emitted by the combustion flame generated at the opening 2 of the refining furnace. In addition, by using a focusing lens in the light acquisition unit 11 to clarify the measurement range, the accuracy of acquiring the spectral radiance can be improved.

The spectral radiance acquisition unit 10 acquires the spectral radiance of the radiation spectrum at a wavelength of interest from the combustion flame generated at the opening 2 of the refining furnace 1, and typically acquires a spectral spectrum that includes this information. The spectral radiance acquisition unit 10 then transmits the spectral radiance information to the calculation unit 20. The wavelength range of the acquired spectral spectrum is, for example, 350 nm to 1000 nm.

Here, the radiation spectrum at the wavelength of interest will be explained. The spectroscopic spectrum obtained from the emission of a combustion flame includes the radiation spectrum, molecular emission spectrum, atomic emission spectrum, etc. Among these, a wavelength that includes the radiation spectrum but does not include the molecular emission spectrum or atomic emission spectrum is selected. For example, a wavelength that includes only the radiation spectrum is selected. The wavelength selected in this way is the wavelength of interest. For example, the molecular emission spectrum of 580 nm to 620 nm caused by the production and disappearance of FeO, the atomic emission spectrum of 589 nm of Na, and the atomic emission spectrum of 767 nm to 770 nm of K are not preferable wavelengths of interest. However, if the wavelength resolution of the spectrometer is high, it is possible to eliminate the effects of molecular emission and atomic emission even in the above ranges.

The selection of the optical path set in the spectral brightness acquisition unit 10 will be described below. In principle, any optical path may be selected as long as it includes the combustion flame generated at the opening 2 of the refining furnace 1 and has a different length. However, if there is almost no difference in the optical path length of the selected optical path, the spectral emissivity ratio described later will be close to 1, and the dust generation rate calculated from it may be less accurate. In addition, it is necessary to consider that the dust concentration (volume ratio in the space) in the combustion flame of the converter furnace mouth is unlikely to be uniform throughout. Simply put, it is expected that the dust concentration is higher closer to the center of the furnace mouth and lower closer to the edge. Therefore, it is preferable to select an optical path that includes the lance 3 of the refining furnace 1 on the extension line of the optical path (effective optical path length: 1/2 of the furnace diameter) and an optical path that does not include the lance 3 of the refining furnace 1 on the extension line of the optical path. More preferably, an optical path that includes the lance 3 of the refining furnace 1 on the extension line of the optical path and an optical path that is slightly shifted from the optical path and does not include the lance 3 of the refining furnace 1 on the extension line of the optical path but is close to the lance 3 (effective optical path length: furnace diameter to 0.8 x furnace diameter, preferably effective optical path length: furnace diameter to 0.9 x furnace diameter, more preferably effective optical path length: furnace diameter) are selected. This makes it possible to measure locations with substantially the same dust concentration while having an optical path difference.

In this disclosure, the spectral luminance acquisition unit 10 is not limited to the form shown in FIG. 1. For example, a light sensor that can acquire the spectral luminance of a specific wavelength using an optical element such as a bandpass filter may be used.

The calculation unit 20 estimates the dust generation rate generated during the operation of the refining furnace based on the spectral luminance of the wavelength of interest transmitted from the spectral luminance acquisition unit 10. The calculation unit 20 is a known computer equipped with a CPU, RAM, ROM, a specified interface, etc.

The calculation unit 20 includes a combustion flame temperature estimation unit that estimates the temperature of the combustion flame for each optical path when the spectral radiance acquisition unit 10 acquires the spectral radiance, a blackbody radiation radiance calculation unit that calculates the blackbody radiance of the wavelength of interest at the estimated combustion flame temperature for each optical path, a spectral emissivity calculation unit that calculates the spectral emissivity for each optical path from the ratio of the spectral radiance acquired by the spectral radiance measurement unit and the blackbody radiance calculated by the blackbody radiation radiance calculation unit, a spectral emissivity ratio calculation unit that selects two of the calculated spectral emissivities and calculates the spectral emissivity ratio, which is the ratio between them, and a dust generation speed estimation unit that estimates the dust generation speed based on a relational equation between the spectral emissivity ratio and the dust generation speed that has been obtained in advance.

The combustion flame temperature estimation unit estimates the temperature of the combustion flame for each optical path when the spectral luminance acquisition unit 10 acquires the spectral luminance. The reason for estimating the temperature of the combustion flame for each optical path is that the combustion flame temperature (radiation temperature) varies spatially. When the spectral luminance acquisition unit 10 acquires a spectral spectrum, the temperature of the combustion flame can be estimated from the spectral spectrum using the principle of a two-color thermometer. The temperature of the combustion flame may also be measured separately using a radiation thermometer. In this case, it is necessary to measure the temperature of the combustion flame simultaneously with the time when the spectral luminance acquisition unit 10 acquires the spectral luminance. Simultaneous does not have to be completely simultaneous. For example, an error of within 1 second is acceptable. Preferably, the temperature of the combustion flame is estimated from the spectral spectrum using the principle of a two-color thermometer.

The blackbody radiation luminance calculation unit calculates the blackbody radiation luminance of the wavelength of interest at the estimated combustion flame temperature for each optical path. The blackbody radiation luminance of the wavelength of interest can be calculated using Planck's law.

The spectral emissivity calculation unit calculates the spectral emissivity (M 0 /M B ) for each optical path from the ratio between the spectral radiance (M ₀ ) acquired by the spectral radiance measurement unit and the _blackbody radiance (M _{B )} calculated by the blackbody radiance calculation unit.

Here, the term "spectral emissivity" is a concept that includes both the absolute value of the spectral emissivity and a value proportional to the spectral emissivity. This is because using a value proportional to the spectral emissivity has little effect on the evaluation of the dust generation rate. The value proportional to the spectral emissivity is the product of the absolute value of the spectral emissivity and a predetermined coefficient that depends on the measurement system. Specifically, the theoretical formula of the temperature-dependent coefficient (relative value) of the "spectral luminance of blackbody radiation" at the wavelength of interest is calculated according to Planck's law, and the "spectral luminance obtained by measurement" is divided by the temperature-dependent coefficient obtained by substituting the "measured radiation temperature (combustion flame temperature)" into the theoretical formula, thereby obtaining a value proportional to the spectral emissivity. However, the evaluation accuracy is improved by obtaining the coefficient that depends on the measurement system in advance using a blackbody furnace and obtaining the absolute value of the spectral emissivity. For example, the absolute value of the spectral emissivity can be obtained by previously obtaining the attenuation rate in a standard blackbody furnace using an apparatus with the same configuration as the apparatus 100.

The spectral emissivity ratio calculation unit selects two of the calculated spectral emissivities and calculates the spectral emissivity ratio, which is the ratio between them.

The dust generation speed estimation unit estimates the dust generation speed based on a relational expression between the spectral emissivity ratio and the dust generation speed that has been calculated in advance.

The spectral emissivity calculated by the spectral emissivity calculation unit is the average spectral emissivity within the light collection range. The spectral emissivity indicates the amount of luminous body (dust) occupying the light collection range when the spectral luminance of the wavelength of interest is acquired by the spectral brightness acquisition unit 10. If the amount of dust is large, the spectral emissivity increases, and if the amount of dust is small, the spectral emissivity decreases. If the optical path length is long, the amount of luminous body occupying the light collection range increases, so the spectral emissivity increases, while if the optical path length is short, the spectral emissivity decreases. If the overlap between dust particles in front and behind can be ignored, the optical path length and the measured spectral emissivity are proportional. On the other hand, if the volume ratio of dust particles in the space increases, the overlap between dust particles cannot be ignored, and the measured spectral emissivity and the dust generation speed are no longer proportional. In this way, the degree of deviation from the proportional relationship, that is, the magnitude of nonlinearity, correlates with the volume ratio of dust.

Whether dust particles can be ignored depends on the depth (optical path length) of the focusing range. This is because the longer the depth and the greater the amount of dust particles in the focusing range, the stronger the influence of dust particles overlapping. Therefore, in the device 100, the spectral luminance is measured at multiple points in the focusing range with different depths, and the effect of dust particles overlapping can be measured by comparing the depth ratio. Then, the spectral emissivity ratio based on the two optical paths is calculated, and the dust generation rate is estimated from this. In this way, the spectral emissivity ratio is calculated using the nonlinearity of the dust generation rate based on the dust particles overlapping. This eliminates the above-mentioned (A) influence on the spectral emissivity of the type of particles that make up the dust and the surface condition, and (B) the influence of dust and water vapor floating on the optical path (from the focusing part to the furnace mouth). In addition, it is also possible to eliminate the influence of (C) the correction factors of the optical system (lens transmittance and optical fiber characteristics).

When multiple similar optical paths are selected, the above-mentioned (A) effects on the spectral emissivity of the type of particles constituting the dust and the surface condition, and (B) effects of dust and water vapor floating on the optical path (from the focusing unit to the furnace opening) can be considered to be equal for each optical path, so factors (A) and (B) can be eliminated by taking the ratio. Furthermore, by using the same equipment configuration for the spectral radiance acquisition unit 10 and the light acquisition unit 11, factor (C) can be eliminated, making detailed corrections to the measurement system unnecessary. Furthermore, even if the spectral radiance acquisition unit 10 and the light acquisition unit 11 do not have to be of the same equipment configuration, detailed corrections to the measurement system can be eliminated by configuring them by combining equipment with known optical properties.

As described above, when estimating the dust generation rate from the spectral emissivity ratio, a relational equation between the spectral emissivity ratio and the dust generation rate that has been determined in advance is used. Such an empirical equation (relational equation) can be determined experimentally or by simulation. For example, an empirical equation may be used in which the spectral emissivity ratio and the gas passage rate near the furnace diameter and the furnace mouth of the refining furnace 1 are variables. Since the gas passage rate is equivalent to the gas generation rate (gas generation amount) based on the amount of oxygen blown from the top and bottom, the gas generation rate may be used as a variable in the empirical equation.

On the other hand, in areas where the dust generation rate is low and the dust concentration in space is small, the spectral emissivity is proportional only to the optical path length, so the spatial concentration of dust cannot be determined. Furthermore, if the dust concentration in space is too high, dust will be present throughout the entire light collection range, resulting in saturation (almost equivalent to uniform surface emission). As a result, the ratio of the spectral emissivity for each optical path will be approximately 1 and will not change. In this way, the method disclosed herein is effective for areas of intermediate dust concentrations.

The intermediate dust concentration range depends not only on the size of the furnace and various blowing conditions including the oxygen supply conditions, but also on the dust properties, particle size distribution, etc., and is therefore considered to be unique to each furnace and cannot be determined only by the operable conditions. Therefore, it is difficult to specify the intermediate dust concentration range, and it is necessary to actually measure and create an empirical formula. The inventors have found that the method of the present disclosure is effective at least in the range of furnace diameters of 0.5 m to 6.5 m and dust concentrations of 1 g/ ^m3 to 200 g/ ^m3 .

The range of the spectral emissivity ratio will now be explained. When the optical paths associated with the two spectral emissivities used in the spectral emissivity ratio are optical path A and optical path B, and the longer optical path is optical path A, the spectral emissivity ratio falls within the range from the ratio of the lengths of optical paths A and B (B/A) to less than 1. It is preferably less than 1, and falls within the range of B/A to B/A + (1 - B/A) x 0.9. By estimating the dust generation rate based on the spectral emissivity ratio falling within this range, the dust generation rate can be estimated with high accuracy.

The dust generation rate estimation device of the present disclosure has been described above using the device 100, which is one embodiment. The dust generation rate estimation device of the present disclosure acquires the spectral luminance of a predetermined wavelength of the combustion flame and estimates the dust generation rate based on the spectral luminance. Therefore, unlike conventional dust generation rate estimation methods, it is configured to be able to operate continuously. In addition, the dust generation rate estimation device of the present disclosure has a high degree of freedom in terms of installation location, as long as the measurement device is placed in a position where the light emission of the combustion flame generated at the opening of the refining furnace can be acquired, and can be installed in a position that is easily accessible by the operator. The dust generation rate estimation device of the present disclosure only requires maintenance of the part that acquires the spectral luminance of the combustion flame (light acquisition part), and does not need to be removed, so the maintenance load is small. For example, it is sufficient to blow off the dust near the light acquisition part with an air duster, etc., and the required maintenance frequency can be reduced to about once per day or less. In addition, by devising a way to prevent dust from adhering to or accumulating on the light acquisition part, it is possible to further reduce the frequency, for example, to once per month or less. Therefore, the maintenance load can be significantly reduced compared to conventional methods. Furthermore, the dust generation rate estimation device of the present disclosure obtains multiple spectral emissivities based on the spectral luminance of the radiation spectrum at the wavelength of interest, and calculates the spectral emissivity ratio from these. The inventors have found that in regions where the gas generation rate is high (regions of intermediate dust concentration), there is a high correlation between the spectral emissivity ratio and the dust generation rate. Therefore, by using the spectral emissivity ratio, the dust generation rate can be estimated with high accuracy. As described above, the dust generation rate estimation device of the present disclosure can operate continuously, has a small maintenance load, and can estimate the dust generation rate with high accuracy.

[Refining furnace]
The refining furnace of the present disclosure controls the refining furnace based on the dust generation rate estimated by the dust generation rate estimation device of the present disclosure. The refining furnace is a furnace for refining molten iron, such as a converter. The control of the refining furnace means, for example, controlling the refining furnace so as to reduce the dust generation rate. Specific means include, for example, changing the height of the lance of the refining furnace, changing the amount of oxygen blown from the top and bottom, and changing the timing and rate of feeding auxiliary materials. The refining furnace of the present disclosure makes it possible to reduce the amount of dust generation.

[Dust generation rate evaluation method]
The dust generation rate estimation method disclosed herein is a method for estimating the generation rate of dust generated during the operation of a refining furnace, and includes a spectral radiance acquisition process for setting a plurality of light paths of different lengths, including a combustion flame generated at an opening of the refining furnace, and acquiring, for each light path, the spectral radiance of a radiation spectrum at a wavelength of interest in the light path; a combustion flame temperature estimation process for estimating, for each light path, the temperature of the combustion flame when the spectral radiance was acquired in the spectral radiance acquisition process; a blackbody radiance calculation process for calculating, for each light path, the blackbody radiance at the wavelength of interest at the estimated combustion flame temperature; a spectral emissivity calculation process for calculating, for each light path, a spectral emissivity from the ratio of the spectral radiance acquired in the spectral radiance measurement process and the blackbody radiance calculated in the blackbody radiance calculation process; a spectral emissivity ratio calculation process for selecting two of the calculated spectral emissivities and calculating a spectral emissivity ratio, which is the ratio between the spectral emissivity ratio and the dust generation rate; and a dust generation rate estimation process for estimating the dust generation rate based on a relational equation between the spectral emissivity ratio and the dust generation rate that has been determined in advance. The details of the dust generation rate estimation method of the present disclosure have been explained in the dust generation rate estimation device of the present disclosure, so explanation thereof will be omitted here.

[Method of controlling a refining furnace]
The refining furnace control method of the present disclosure controls the refining furnace based on the dust generation rate estimated by the dust generation rate estimation method of the present disclosure. The contents of the refining furnace control method of the present disclosure have been described in the refining furnace of the present disclosure, so description thereof will be omitted here.

The present disclosure will be further explained below using examples.

[Example 1]
The dust generation rate was estimated using a small 2-ton converter. The light paths (1) to (3) were used (see Figure 2).
(1) The lance is not included in the extension of the optical path, but the optical path is close to the lance (effective optical path length: furnace diameter)
(2) An optical path including the lance on the extension line of the optical path (effective optical path length: 1/2 of the furnace diameter)
(3) An optical path that does not include the lance on the extension line of the optical path (effective optical path length: 1/4 of the furnace diameter)
Although the effective optical path length in (1) is not exactly the same as the furnace diameter, it is considered to be the same as the furnace diameter to simplify the calculation.

Here, the same optical system (collecting lens, etc.) was used for all the spectral radiance acquisition sections. The spectral radiance acquisition section also acquired the spectral radiance at the wavelength of interest of 700 nm. The temperature of the combustion flame was estimated using the principle of a two-color thermometer based on the radiance ratio of wavelengths of 700 nm and 900 nm. The spectral emissivity was then calculated for each optical path from the ratio of the calculated spectral radiance to the blackbody radiation radiance, and the spectral emissivity ratios (2)/(1) and (3)/(1) were calculated. Furthermore, the converter exhaust gas was sampled at regular intervals and passed through a filter to collect dust.

Figure 3 shows the relationship between the spectral emissivity ratio and the amount of filters collected per unit time. In the figure, circles represent the spectral emissivity ratio (2)/(1), and crosses represent the spectral emissivity ratio (3)/(1). Figure 4 shows the relationship between the amount of filters collected per unit time estimated from the spectral emissivity ratio (2)/(1) and the actual amount of filters collected per unit time. Here, the conversion from the spectral emissivity ratio to the amount of filters collected per unit time was made using the equation for the approximate straight line in Figure 3.

Figure 3 confirms that there is a strong correlation between the spectral emissivity ratio and the filter collection amount. Also, Figure 4 confirms that there is a strong correlation between the filter collection amount estimated from the spectral emissivity ratio and the actual filter collection amount. The filter collection amount per unit time correlates with the dust generation rate. Therefore, it has been found that the present disclosure makes it possible to estimate the dust generation rate with high accuracy.

[Example 2]
The dust generation rate was evaluated using a 300 ton converter, and the operation of the converter was controlled based on the evaluation. The optical paths (1) and (2) were used. Here, the same optical system (condenser lens, etc.) was used for all the spectral radiance acquisition units. The spectral radiance acquisition unit acquired the spectral radiance at the wavelength of interest of 700 nm. The temperature of the combustion flame was estimated using the principle of a two-color thermometer based on the radiance ratio of wavelengths of 700 nm and 900 nm. Then, the spectral emissivity was calculated for each optical path from the ratio of the calculated spectral radiance to the blackbody radiation radiance, and the spectral emissivity ratio (2)/(1) was calculated. The actual dust generation rate (index value) was calculated from the amount of dust collected from the dust collection water.

The amount of dust collected from the dust collection water is the ratio of the weight of dust contained in the sampled dust collection water to the amount of sampled water when the dust collection water is sampled at a specified interval. This amount of dust can be obtained, for example, by a filtration analysis that improves on "JIS K 0102 14.1 Suspended solids." Normally, in the above-mentioned "JIS K 0102 14.1 Suspended solids," an appropriate amount is poured into a filter, but since representativeness cannot be obtained for dust with a wide particle size distribution, the entire sample collected is filtered to obtain the dust amount.

Figure 5 shows the relationship between the spectral emissivity ratio and the measured dust generation rate (index value) and the elapsed time. Here, at the 2 minute point in Figure 5, the converter operation (lance height and oxygen flow rate) was controlled to reduce the dust generation rate.

Figure 5 confirms that the dust generation rate can be reduced by the operator controlling the operation of the converter while observing the change over time in the spectral emissivity ratio.

Reference Signs List 1 Refining furnace 2 Opening 3 Lance 10 Spectral radiance acquisition unit 11 Light acquisition unit 12 Spectrometer 20 Calculation unit 100 Dust generation rate evaluation device

Claims (6)

An apparatus for estimating the generation rate of dust generated during the operation of a refining furnace,
A spectral radiance acquisition unit that includes a combustion flame generated at an opening of the refining furnace, sets a plurality of optical paths having different lengths, and acquires the spectral radiance of a radiation spectrum at a wavelength of interest in each of the optical paths;
a combustion flame temperature estimation unit that estimates a temperature of the combustion flame for each optical path when the spectral radiance acquisition unit acquires the spectral radiance;
a blackbody radiation luminance calculation unit that calculates a blackbody radiation luminance of the wavelength of interest at the estimated temperature of the combustion flame for each optical path;
a spectral emissivity calculation unit that calculates a spectral emissivity for each of the optical paths from a ratio of the spectral radiance acquired by the spectral radiance acquisition unit and the blackbody radiance calculated by the blackbody radiance calculation unit;
a spectral emissivity ratio calculation unit that selects two of the calculated spectral emissivities and calculates a spectral emissivity ratio, which is a ratio between the two;
a dust generation rate estimation unit that estimates the dust generation rate based on a relational expression between a spectral emissivity ratio and a dust generation rate that has been obtained in advance;
A dust generation rate estimation device comprising: The dust generation rate estimation device according to claim 1, wherein the optical paths include an optical path that includes the lance of the refining furnace on the extension line of the optical path, and an optical path that does not include the lance of the refining furnace on the extension line of the optical path. A refining furnace that controls the refining furnace based on the dust generation rate estimated by the dust generation rate estimation device described in claim 1 or 2. A method for estimating the dust generation rate generated in the operation of a smelting furnace, comprising:
A spectral radiance acquisition step of setting a plurality of optical paths having different lengths, including a combustion flame generated at an opening of the refining furnace, and acquiring the spectral radiance of the radiation spectrum at a wavelength of interest in each of the optical paths;
a combustion flame temperature estimating step of estimating a temperature of the combustion flame for each optical path at the time when the spectral radiance is acquired in the spectral radiance acquiring step;
a blackbody radiation luminance calculation step of calculating a blackbody radiation luminance of the wavelength of interest at the estimated temperature of the combustion flame for each optical path;
a spectral emissivity calculation step of calculating a spectral emissivity for each of the optical paths from a ratio of the spectral radiance acquired in the spectral radiance acquisition step and the blackbody radiance calculated in the blackbody radiance calculation step;
a spectral emissivity ratio calculation step of selecting two of the calculated spectral emissivities and calculating a spectral emissivity ratio, which is a ratio between the two;
a dust generation rate estimation step of estimating the dust generation rate based on a relational expression between a spectral emissivity ratio and a dust generation rate that has been obtained in advance;
A dust generation rate estimation method comprising: The dust generation rate estimation method according to claim 4, wherein the optical paths include an optical path that includes the lance of the refining furnace on an extension line of the optical path, and an optical path that does not include the lance of the refining furnace on an extension line of the optical path. A method for controlling a refining furnace, which controls the refining furnace based on the dust generation rate estimated by the dust generation rate estimation method according to claim 4 or 5.