JP4318614B2 - Blast furnace operation method - Google Patents

Description

  The present invention relates to a method for operating a blast furnace.

The blast furnace is charged with iron ore and coke as a reducing agent from the upper part, and blown with hot air from the lower part to cause a series of reactions such as reduction and melting of the iron ore to produce pig iron. A series of reactions such as iron ore reduction and dissolution can be efficiently performed by adjusting the particle size of the furnace interior so that an appropriate gas flow velocity distribution in the radial direction can be obtained in the blast furnace and appropriately controlling the blowing conditions. It will be possible to operate efficiently with a low fuel ratio.
A plurality of openings or tuyere are formed in the side wall of the lower part of the blast furnace, and hot air (including steam) that passes through the hot stove, hot air pipe, hot air annular pipe, and hot air branch pipe through the tuyere. Air). Furthermore, pulverized coal is blown from this tuyere.

Inside the blast furnace, in front of the tuyere, a hollow portion in which coke called so-called “raceway” exists in a significantly sparse state is formed by air blown from the tuyere. In the raceway near the tuyere, most of the coke charged into the blast furnace and pulverized coal injected from the tuyere are combusting, and it is necessary to dissolve and react the necessary reducing gas and iron ore in the furnace. Most of the heat required is supplied from this part. In other words, the pulverized coal is a fuel combusted in a raceway and also serves as a reducing agent for iron ore.
Since it is difficult to accurately determine the size and shape of the raceway, the distance between the deepest part of the raceway and the tuyere in the blast furnace diameter direction is the raceway depth, and the size and shape of the raceway has been used. Has been treated as a representative value.

However, among these raceways, a particular raceway may be distorted or collapsed due to various causes. When the raceway collapses, hot metal in the blast furnace may flow into the tuyere and cause tuyere damage. To prevent such abnormal conditions, blast furnace operation that prevents the raceway from collapsing has been conventionally performed. Various methods have been considered.
For example, in Patent Document 1, a high-speed camera is installed for each tuyere, and the particle size and density are estimated by photographing the turning coke in the raceway. A technique is disclosed in which the raceway depth is estimated using a penetration factor, and the amount of fuel, such as pulverized coal, injected into the raceway is adjusted based on the raceway depth to prevent its collapse. .
Japanese Patent Laid-Open No. 1-20202 (pages 2 to 5)

However, in the technique of Patent Document 1, even if the fuel injection amount is variously devised, the size and shape of the raceway to be controlled, that is, the raceway depth is an estimated value. It was impossible, and it was difficult to prevent the raceway from becoming erratic and collapsing.
Accordingly, in view of the above problems, the present invention provides a method for operating a blast furnace characterized by adjusting the amount of fuel injected from the tuyere to prevent the raceway from collapsing based on the actually measured depth of the raceway. It is intended to provide.

In order to achieve the above object, the present invention takes the following technical means.
That is, the technical means for solving the problems in the present invention is a method of operating a measured raceway in a blast furnace operating method in which a plurality of tuyere are provided in the lower circumferential direction and a raceway is formed in the vicinity of the tuyere. Based on the distance to the deepest part, the fuel injection amount from the tuyere is adjusted to prevent the raceway from collapsing or shrinking.
According to this technical means, by adjusting the fuel injection amount from the tuyere based on the actually measured depth of the raceway, it is possible to prevent the raceway from collapsing or shrinking, and further to the tuyere damage. It becomes like this.

  Specifically, the inventors of the present application have found the relationship between the presence or absence of fuel injection from the tuyere, the amount of air blown from the tuyere, and the change in the shape of the raceway as shown in FIG. 2 and FIG. It is shown that raceway collapse can be prevented by reducing or blocking early. Therefore, it is possible to prevent the target raceway from collapsing or shrinking by using the above relationship while actually measuring the raceway depth. Since the raceway depth is not an estimated value but an actually measured value, it is possible to effectively and reliably prevent the raceway from becoming distorted.

Further, the technical means for solving the problems in the present invention is characterized in that the amount of fuel blown is adjusted when the amount of air blown from the tuyere is reduced in the blast furnace air reduction process.
Although it has been found as a track record in the field that raceway collapse is likely to occur when the air flow from the tuyere is reduced due to temporary cessation of the blast furnace, that is, in the wind reduction process, this technical means is used. Thus, the fuel injection amount from the tuyere is adjusted based on the actually measured depth of the raceway, and the raceway can be prevented from collapsing or shrinking, and further, the tuyere breakage.

Further, the technical means for solving the problem in the present invention is that the fuel blown from the tuyere is pulverized coal, and when the distance to the deepest part of the raceway is decreasing, the pulverized coal is blown from the tuyere. It is characterized by reducing or blocking the amount.
According to this technical means, it is possible to prevent the raceway depth from being reduced, that is, the raceway from being collapsed or reduced, by reducing or blocking the amount of pulverized coal injection at an early stage.
Further, the technical means for solving the problem in the present invention is that the fuel injected from the tuyere is pulverized coal, and an upper limit of the amount of pulverized coal injection necessary to maintain the distance to the deepest part of the raceway is obtained in advance. In addition, on the basis of the upper limit amount, the amount of pulverized coal blown from the tuyere is reduced or blocked.

According to this technical means, by reducing or shutting down the pulverized coal injection from the tuyere based on the upper limit of the pulverized coal blowing amount obtained in advance, the raceway collapses or shrinks, and eventually the tuyere It becomes possible to prevent damage.
The technical means for solving the problems in the present invention is that the depth of the raceway is:
A transmission step of transmitting a transmission wave that is frequency-modulated toward the deepest part of the raceway through the tuyere, a deepest part reflected wave that is generated when the transmission wave is reflected at the deepest part of the raceway, and a deepest part A receiving step for receiving a non-deepest part reflected wave generated by reflection at a point other than the above, and a circularly polarized wave selection for selectively removing a predetermined circularly polarized wave included in each reflected wave obtained in the receiving step A beat wave generating step for generating a beat wave by superimposing an output of the circularly polarized wave selecting step and the transmission wave, and a band removing step for removing the non-deepest part reflected wave included in the beat wave And a Fourier transform processing step for deriving a frequency spectrum by performing Fourier transform on the output of the band removal step, and a distance calculating step for calculating a distance from the distribution of the frequency spectrum to the deepest part of the raceway. Is the fact characterized.

  According to this technical means, in the transmission process, a transmission wave that is frequency-modulated toward the deepest part of the raceway is transmitted through the tuyere, and in the reception process, the transmission wave is reflected at the deepest part of the raceway. And a non-deepest part reflected wave generated by reflection at a portion other than the deepest part, and a circular deflection wave selection step, and a predetermined included in each reflected wave obtained in the reception step. The circularly polarized wave is selectively removed, and in the beat wave generating process, the output of the circularly polarized wave selecting process and the transmission wave are superimposed to generate a beat wave, and the non-band included in the beat wave is generated in the band removing process. The reflected wave is removed from the deepest part, the frequency spectrum is derived by Fourier transforming the output of the band removal process in the Fourier transform process, and the distance from the frequency spectrum distribution to the raceway deepest part is calculated in the distance calculation process. Then, It is possible to actually measure the Suwei depth.

Further, the technical means for solving the problem in the present invention is that the circularly polarized wave selection step is a circularly polarized wave in which the transmission wave is deflected in a certain direction, and the transmission wave is transmitted from the reflected wave obtained in the reception step. A circularly polarized wave deflected in the opposite direction to the wave is extracted.
According to this technical means, it is possible to remove the reflected wave that is double-reflected at the deepest part of the raceway and other places (for example, the inner wall surface of the hot air branch pipe) and whose circular deflection direction is the same as the transmitted wave. Measurement accuracy can be improved.
Further, the technical means for solving the problem in the present invention is that the band removing step estimates the frequency component of the non-deepest part reflected wave in advance and uses a band removing filter that removes only the frequency component to generate a beat wave. The frequency component is removed from the signal.

According to this technical means, the frequency component of the non-deepest part reflected wave reflected at a place other than the deepest part of the raceway is estimated, and the frequency component is removed from the beat wave by the band elimination filter that removes only this frequency component. Measurement accuracy can be improved.
Further, the technical means for solving the problems in the present invention is characterized in that the distance calculating step calculates a distance according to the following equation based on the distribution of the frequency spectrum of the beat wave.

Here, l: distance between tuyere and raceway deepest part, t: round-trip time of transmission wave, T: period, fb: beat wave frequency, F: frequency modulation width, c: speed of transmission wave.
According to this technical means, it is possible to measure the distance from the frequency spectrum distribution of the beat wave to the deepest part of the raceway.
The technical means for solving the problems in the present invention is characterized in that the transmission wave is a microwave.
According to this technical means, since the transmission wave is a microwave, it is hardly affected even in a high temperature environment, an environment with a lot of dust and water vapor, or an environment with high luminance. In addition, since the directivity of the transmission wave is high, it is possible to emit the transmission wave from a thin tuyere.

The most preferable technical means for solving the problem is a blast furnace operating method in which a plurality of tuyere are provided in the circumferential direction and a raceway is formed in the vicinity of the tuyere. When reducing the air flow from the tuyere, measure the distance to the deepest part of the raceway, and when this measured distance is decreasing, pulverized coal from the tuyere to prevent the raceway from collapsing or shrinking It is characterized by reducing or blocking the blowing amount.

  According to the present invention, it is possible to adjust the fuel injection amount from the tuyere to prevent the raceway from collapsing based on the actually measured depth of the raceway.

Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings.
The blast furnace is charged with iron ore and coke as a reducing agent from the upper part, and blown with hot air from the lower part to cause a series of reactions such as reduction and melting of the iron ore to produce pig iron.
As shown in FIG. 4, a plurality of (several dozen) openings or tuyere 3 are formed in the circumferential direction 2 on the lower side wall 2 of the blast furnace 1. The hot air (air containing steam) that has passed through the hot air annular pipe 4 and the hot air branch pipe 5 is blown. Further, from the tuyere 3, pulverized coal that acts as a reducing agent as well as fuel is blown.

In the blast furnace 1, in front of the tuyere 3, a hollow portion 6 in which coke called so-called "raceway" exists in a significantly sparse state is formed by the air blown from the tuyere 3. In the raceway 6 in the vicinity of the tuyere 3, most of the coke charged in the blast furnace 1 and pulverized coal injected from the tuyere 3 are combusted, and necessary reducing gas, iron ore, etc. are burned in the furnace. Most of the heat required for dissolution and reaction is supplied from this part.
Although the size and shape of the raceway 6 are considered to have a very significant influence on the situation and productivity of the blast furnace 1, it is necessary to accurately grasp the size and shape of the raceway 6 during operation. Therefore, the distance between the deepest part of the raceway and the tuyere 3 in the radial direction of the blast furnace is taken as the raceway depth and has been treated as a value representative of the size and shape of the raceway 6.

FIG. 1 shows a horizontal cross section of such a raceway 6. Under normal operating conditions, even for a raceway 6 that maintains a certain size and shape,
(A) In the raceway 6, pulverized coal is appropriately input, and the state is not only coke (all coke). By introducing pulverized coal, the temperature in the furnace temporarily decreases, or the amount of coke descending from above decreases, so that the size and shape of a specific raceway 6 is different. It becomes distorted or collapses.
(B) In the blast furnace 1 wind-reducing operation (operation to reduce the amount of hot air blown into the blast furnace 1) once every several months, it may eventually stop while reducing the blowing of hot air from the tuyere 3. At that time, a specific raceway 6 may be distorted or destroyed.

In order to solve this problem, the present inventor has discovered the characteristics of the raceway depth as shown in FIGS.
FIG. 2 shows the raceway area ratio on the horizontal axis and the deviation rate on the vertical axis. The black circle data shows the all coke state, and the white circle data shows the pulverized coal blowing state.
The raceway area ratio is the raceway cross-sectional area / the blast furnace cross-sectional area, and the larger the value, the larger the shape of the raceway 6, in other words, a state where a large amount of hot air is blown at high speed. .

The deviation rate is the measured raceway depth / calculated raceway depth. The closer to 0, the smaller the actual raceway 6 depth is compared to the theoretical value, and the raceway 6 becomes more erratic, leading to tuyere damage. It shows that it is easy.
In the figure, since the slope of the white circle is large, it can be seen that in the pulverized coal blowing state, when the air volume is small, the raceway depth is shallow and the tuyere breaks easily.
Therefore, when the tuyere 3 with a small tuyere diameter or the blowing speed of hot air is low, the decrease in the raceway depth can be mitigated by reducing the amount of pulverized coal blowing, and tuyere damage can be prevented.

FIG. 3 shows the relationship between the amount of hot air blown from the tuyere 3 and the raceway depth. The black circle is an actual measurement value in a pulverized coal blowing state, and the white circle is a theoretical calculation value.
As can be seen, as the air volume from the tuyere 3 decreases, the difference from the theoretical value increases and the raceway depth becomes extremely small. That is, the raceway 6 collapses and the tuyere breaks easily. In fact, there has been reported an example in which the tuyere 3 is damaged in the vicinity of an air flow rate of 4000 Nm ³ / min.
Therefore, it is expected that the tuyere breakage at the time of wind reduction can be avoided by changing the timing of shutting off the pulverized coal to a higher air volume side than the conventional one (for example, an air flow rate of 4000 Nm ³ / min or more). it can.

In consideration of the characteristics of these raceways 6, the relationship between the raceway depth and the amount of pulverized coal injection is clarified. Based on this relationship, the tuyere 3 is used to prevent the raceway 6 from collapsing or shrinking. Adjust the amount of pulverized coal injection.
In order to solve the problem (a), using a raceway depth measurement device, which will be described later, a plurality of raceway depths provided in the circumferential direction of the blast furnace 1 are measured, and data is obtained as shown in FIG. After organizing, keep track of the raceway 6 where the sprouting is progressing (shallow depth).

FIG. 11 schematically shows a horizontal cross section of the surface where the tuyere 3 is attached in the blast furnace 1, and shows that 38 tuyere 3 are attached in the circumferential direction. The depth of the raceway 6 corresponding to each tuyere 3 is indicated by the radial distance. The data points are plotted on the outer side in the radial direction, that is, the closer the graph is to a circle, the more suitable the raceway depth is. On the contrary, the closer to the inner side in the radial direction, the more the raceway 6 collapses.
When the scale of the blast furnace 1 has an internal volume of 1500 m ³ , the raceway depth is usually 1.0 to 2.0 m, and when the depth is 1.0 m or less, the raceway 6 is It is thought that the collapse is progressing. In particular, the raceway 6 in the vicinity of the taphole has a shape in which the shape of the raceway 6 is likely to change greatly due to a change in the condition in the blast furnace caused by the tapping.

FIG. 12 shows the relationship between the hot air blowing amount and the pulverized coal blowing amount with respect to each raceway depth at each raceway depth, and is obtained from the experimental results as shown in FIGS. 2 and 3. . For example, when it is desired to maintain the raceway depth at 1.5 m, if attention is paid to the curve of L = 1.5 m, the hot air blowing amount and the corresponding pulverized coal blowing amount can be obtained.
According to the curve of L = 1.5 m, for example, when the blowing rate is 6500 Nm ³ / min, the pulverized coal blowing rate is approximately 60000 kg / hr, but when the blowing rate is reduced to 5500 Nm ³ / min, The amount of pulverized coal injection is preferably about 10,000 kg / hr.

Therefore, the raceway depth curve corresponding to FIG. 12 is selected for the raceway 6 having the possibility of collapsing, which is found from FIG. 11, and the optimum pulverized coal injection amount with respect to the current blowing amount is obtained. A smaller amount is blown from the pulverized coal lance 14. By doing so, excessive pulverized coal can be prevented from being blown in, and an appropriate raceway depth can be maintained.
Also, the raceway depth is always measured without using the relationship between the raceway depth and the amount of pulverized coal injection as shown in FIG. 12, and the depth is likely to be shallow (the raceway is likely to collapse). Immediately before the sign appears, the amount of pulverized coal may be reduced or blocked.

In order to solve the problem (b) and temporarily stop the blast furnace 1, the raceway 6, particularly one having a small tuyere diameter, may be broken during a wind-reducing operation during the blast furnace suspension process. While measuring the depth of the raceway 6 formed in the above, the amount of pulverized coal blown from the tuyere 3 is adjusted based on the distance.
That is, during the wind-reducing operation, the depth of each raceway 6 provided in the circumferential direction of the blast furnace 1 is measured every moment using a raceway depth measurement device described later, and the crazing is proceeding (depth). Keep track of Raceway 6.

For the raceway 6 that is likely to collapse, the curve corresponding to the raceway depth is selected in FIG. 12 before the occurrence of stagnation or collapse, and the optimum pulverized coal injection amount with respect to the current air flow rate. And an amount less than that amount is blown from the pulverized coal lance 14. By shutting down the pulverized coal blowing before the air flow becomes 4000 Nm ³ / min or less, the raceway can be reliably prevented from collapsing.
When the pulverized coal blowing is reduced, the amount of pulverized coal to be blown into the entire blast furnace 1 needs to be constant. Therefore, it is preferable that the reduced amount of pulverized coal be supplied from the other tuyere 3. It has been found from actual results at the site that the reduction rate of hot air blowing should be about 50 Nm ³ / min.

Further, without using the relationship between the raceway depth and the amount of pulverized coal injection as shown in FIG. 12, the raceway depth is always measured in the process of reducing the wind speed during temporary blast furnace suspension, and the depth is shallow. The amount of pulverized coal blown may be reduced or cut off just before a sign that is likely to occur (the raceway is likely to collapse).
In the operation of such a blast furnace 1, it is indispensable to actually measure the raceway depth in real time as fast as possible. In an operation method in which the raceway depth is replaced with an estimated value, effective blast furnace operation is possible. Is impossible.

FIG. 4 is a cross-sectional view showing a raceway depth measuring device used in the operation method according to the present invention, in which the measuring device is attached to the proximal end side of the hot air branch pipe 5.
As shown in this figure, an opening having a diameter of several centimeters is formed in a furnace wall brick 8 forming the side wall 2 of the blast furnace 1, and a cylindrical tuyere 3 is fitted into this opening. The tuyere 3 is provided at almost equal intervals over the entire circumference of the lower part of the blast furnace 1, and is arranged so that the hot air branch pipe 5 is inserted into the tuyere 3.
The hot air branch pipe 5 is composed of a blow pipe 10 inserted into the tuyere 3, a lower bend 11 projecting substantially perpendicularly on the proximal end side of the blow pipe 10, and an upper bend 12 extending to the lower bend. The upper bend 12 is connected to the hot air annular tube 4. Each member is hollow so that hot air can flow, and the inner surface 13 is lined with a refractory.

The blow pipe 10 is provided with a plurality of pulverized coal lances 14 (pulverized coal charging pipes) for injecting pulverized coal as a reducing agent into the blast furnace 1, and at the base end side of the blow pipe 10. An opening 15 is formed.
As shown in FIG. 4, the present measuring apparatus shows an output result from the apparatus main body 17, a waveguide 18 extending therefrom, a columnar antenna 19 provided at the tip of the waveguide 18, and the output from the apparatus main body 17. And a display 20 for displaying.
The antenna 19 has a conical recess 21 formed therein in order to efficiently emit a transmission wave, which is a microwave, to the proximal end side of the blow pipe 10 as shown in detail in FIG. The tuyere glasses 16 are provided in the opening 15 formed in the, and the antenna 19 is disposed so as to be adjacent to the tuyere glasses 16. The antenna 19 may be provided so as to be fitted into the tuyere glasses 16 and is arranged so as to be fitted directly into the opening 15 formed on the proximal end side of the blow pipe 10. There is no problem even if it is integrated.

A transmission wave generated in the apparatus main body 17 is guided by the waveguide 18 and emitted from the antenna 19 toward the deepest portion 7 of the raceway 6 through the blow pipe 10 and the opening of the tuyere 3. The emitted transmission wave is reflected by the raceway deepest portion 7 and returned, and then received by the antenna 19 and guided to the apparatus main body 17 through the waveguide 18.
In the apparatus main body 17, the distance from the tuyere 3 to the deepest part 7 of the raceway is calculated using the transmitted wave and the reflected wave (received wave).
The calculated raceway depth and information related thereto (for example, a frequency spectrum described later) are output to the display 20. The display device 20 can display various information in a graphic form.

FIG. 5 shows the configuration of the apparatus main body 17. In other words, the measuring apparatus according to the present invention includes a transmission unit 23 that transmits a transmission wave that is frequency-modulated toward the deepest portion 7 of the raceway 6, and the transmission unit 23 transmits a microwave used for measurement. A microwave generation unit 24 to be generated, a frequency modulation unit 25 that applies frequency modulation to the microwave, a waveguide 18, and an antenna 19 are provided.
In addition, a receiving unit 26 is provided for receiving the deepest part reflected wave generated by reflecting the transmitted wave at the deepest part 7 of the raceway 6 and the non-deepest part reflected wave generated by reflecting other than the deepest part 7. The receiving unit 26 includes an antenna 19 and a waveguide 18.

In addition, a circular deflection wave selection unit 31 that selectively removes a predetermined circular deflection wave included in each reflected wave obtained by the reception unit 26, an output of the circular deflection wave selection unit 31, and the transmission wave And a Fourier transform of the output of the band removing step, a beat wave generating unit 27 for generating a beat wave, a band removing unit 28 for removing the non-deepest part reflected wave included in the beat wave, A Fourier transform processing unit 29 for deriving a frequency spectrum and a distance calculation unit 30 for calculating a distance from the frequency spectrum distribution to the raceway deepest portion 7 are provided.
This measuring device may be attached to a plurality of or a plurality of tuyere 3 provided in a large number, or one measuring device may be moved sequentially for each tuyere 3 to perform measurement.

In addition, since this measuring apparatus is installed in the base end side of the hot air branch pipe 5 of high temperature (900-1200 degreeC), it will receive the heat by the radiant heat and conduction from the hot air branch pipe 5 and the blast furnace 1 main body. However, since the antenna 19 provided integrally with the tuyere 3 and the device main body 17 composed of electronic parts and the like and weak against heat are separated by the waveguide 18, the device main body 17 is cooled. There is no need to provide a means, and the manufacturing cost can be reduced.
Next, signal processing in this measurement apparatus will be described with reference to FIGS.
First, in the transmission unit 23, the generated microwave is frequency-modulated to form a transmission wave, and this transmission wave is emitted from the antenna 19 to the deepest raceway portion 7 through the blow pipe 10 and the tuyere 3. (Transmission process, S61)
More specifically, a microwave is generated by a microwave generator 24 composed of a semiconductor element such as a Gunn diode, and the microwave is frequency-modulated by a frequency modulator 25 so as to be a sawtooth wave. The frequency modulation referred to here is to perform control such that “the frequency changes in proportion to time”. The frequency-modulated microwave becomes a frequency-modulated continuous wave (FM-CW).

This frequency-modulated continuous wave is guided to the antenna 19 via the waveguide 18 as a transmission wave, and is emitted from there to the raceway deepest portion 7.
A part of the transmission wave is transmitted to a beat wave generating unit 27 described later by a circulator (directional coupler) in order to generate a beat wave described later.
The transmission wave emitted by the transmission unit 23 becomes the deepest part reflected wave generated by reflecting at the deepest part 7 of the raceway 6 and the non-deepest part reflected wave generated by reflecting from other than the deepest part 7, and received. The signal is received by the unit 26, that is, the antenna 19, and transmitted to the circulator through the waveguide 18. (Reception process, S62)
In the present embodiment, the reflection of the transmitted wave in the portion other than the deepest portion 7 includes reflection from the blow pipe inner wall surface 13, the opening 15 of the lower bend, the opening 37 of the pulverized coal lance, and the like.

Each reflected wave (received wave) that has passed through the circulator is introduced into the beat wave generator 27 via a circularly polarized wave selector 31 described later.
In the beat wave generation unit 27, the transmission wave and the reception wave are mixed, and a beat wave is generated. (Beat wave generation process, S64)
A beat wave is the result of interference when two waves with slightly different frequencies overlap, and is a “beating wave” in the sonic world. It is known that this is a difference in frequency.

When the frequency of the beat wave is clarified, the distance to the object (in this embodiment, the raceway deepest part 7) that reflects the transmission wave emitted from the antenna 19 is calculated using the beat wave frequency. It is clear from the laws of physics that it is possible. Therefore, the beat wave is subjected to Fourier transform using an algorithm such as FFT in the Fourier transform processing unit 29 through a band removing unit 28 described later, and a frequency spectrum is obtained. (Fourier transform processing step, S66)
An example of the obtained frequency spectrum is shown in FIG.

  Next, based on the distribution of the frequency spectrum, for example, the peak value, the distance to the raceway deepest portion 7l is obtained using the following equation. (Distance calculation step, S67)

Where l: raceway depth (distance between tuyere 7 and raceway deepest part 7), t: round-trip time of microwave, T: period (frequency sweep time), fb: beat wave frequency, F: frequency modulation width C: speed of light.
By performing the above-described steps, the raceway depth can be obtained. However, in the case of this embodiment, since the transmission wave which is a microwave is transmitted through the hollow part of the blow pipe 10 provided in the tuyere 3, the deepest part reflection which is a reflected wave from the deepest part 7 In addition to the wave, the non-deepest part reflected wave, which is a reflected wave from the non-deepest part 7, for example, the openings 36 and 37 of the lower bend 11 and the pulverized coal lance 14, is included in the received wave.

In the frequency spectrum shown in FIG. 8, peak 2 is the frequency of the beat wave caused by the deepest reflected wave, and peak 1 is the frequency of the beat wave caused by the non-deepest reflected wave.
Therefore, even if the frequency spectrum of FIG. 8 is used as it is, the peak value (peak 1) is obtained, and the distance is obtained by the distance calculating step, the raceway depth is not obtained.
Therefore, in the present embodiment, the frequency component of the non-deepest part reflected wave whose position (distance) is known in advance is estimated, and a band elimination filter (a band elimination filter or a notch filter that removes only this frequency component). A band removing step of removing the frequency component from the beat wave by a filter). (S65)
Specifically, in order to remove the non-deepest part reflected wave having the frequency of peak 1 in FIG. 8, as shown in FIG. 7, the vicinity of the frequency of peak 1 is blocked, and the frequency band away from peak 1 has a characteristic of passing well. A band elimination filter is prepared, and a beat wave is passed through this filter. Specifically, this band elimination filter is an analog filter composed of an electronic circuit such as an IC.

The result of inputting the output wave that has passed through the band removal step to the above-described Fourier transform processing step (S66) is as shown in FIG. 9, and the peak value of the frequency spectrum becomes the frequency peak2 of the deepest reflected wave, and The raceway depth is obtained with high accuracy through a distance calculation step.
In the case of this embodiment, in order to prevent the reflected wave reflected by the raceway deepest part 7 from being reflected again by the inner wall 2 of the blow pipe 10 (double reflection) and causing an error in distance measurement. The measuring apparatus has a configuration in which the received wave from the circulator passes through the circularly polarized wave selector 31 and the output is input to the beat wave generator 27.

In this circularly polarized wave selection unit 31, the circularly polarized wave selection step S63 shown in FIG. 6 is performed, and the following signal processing is performed.
That is, the transmission wave is a wave in which the combined vector of the electric field and the magnetic field spirals in a clockwise direction (a right-handed circularly polarized wave). The reflected wave is removed. In other words, only the antiphase reflected wave is taken out.
This is because when the transmission wave is a right-handed circularly polarized wave, the reflected wave reflected by the raceway deepest portion 7 becomes a left-handed circularly-polarized wave whose combined vector is counterclockwise. This is based on the property that once the electromagnetic wave is reflected, its deflection direction is reversed.

When this property is used, when the transmission wave reflected by the deepest portion 7 is reflected by another surface (for example, the inner surface 13 of the blow pipe 10), (transmission wave) clockwise → (reflection) left rotation → (Reflection) It becomes right-handed and is in phase with the transmission him, and is reliably removed by the circularly polarized wave selection unit 31.
Thus, the raceway depth can be measured with high accuracy by not receiving the reflected wave that causes double reflection.
In the description, the deflection direction of the transmission wave is a right turn, but there is no problem even if it is a left turn. At this time, the deflection direction of the double reflected wave to be removed also turns left.

The present invention is not limited to the above embodiment.
That is, the transmission wave is not limited to the microwave. For example, it may be an ultra high frequency wave having a slightly different wavelength.
Further, in the present embodiment, the frequency spectrum distribution, that is, the measurement up to the deepest part of the raceway is measured based on the maximum peak value. Then, the distance to the coke turning in the raceway cavity can be measured, and the behavior of the raceway can be further clarified.

The concept of this operation method is not limited to blast furnaces, but can be applied to vertical furnaces.
Further, in order to obtain the raceway depth, signal processing is performed using the various steps S61 to S67 as described above, but the circularly polarized wave selection step S63 and the band removal step S65 are not necessarily required, and the received wave In consideration of the state of occurrence of noise (other than the reflected wave from the raceway deepest portion 7) included therein, each step S63 or S65 may be appropriately provided.

It is the figure which showed a part of cross section of a blast furnace. It is the figure which showed the raceway area ratio and the deviation rate. It is the figure which showed the ventilation volume and raceway depth from a tuyere. It is sectional drawing which shows that the measuring apparatus is attached to the tuyere. It is the figure which showed the structure of the measuring apparatus. It is the flowchart which showed the measuring method. It is a figure which shows the characteristic of a zone | band removal filter. It is a frequency spectrum of a beat wave including a non-deepest part reflected wave. It is a frequency spectrum of a beat wave including only the deepest reflection wave. It is an enlarged view of a hot air branch pipe base end side. It is a figure which shows the distribution state of the raceway depth in a blast furnace circumferential direction. It is the figure which showed the amount of pulverized coal injection in this operation method.

DESCRIPTION OF SYMBOLS 1 Blast furnace 3 tuyere 6 raceway 7 raceway deepest part 23 transmission part 26 reception part 27 beat wave generation part 28 band removal part 29 Fourier transform processing part 30 distance calculation part

Claims (7)

In the operation method of the blast furnace in which a plurality of tuyere (3) are provided in the circumferential direction and a raceway (6) is formed in the vicinity of the tuyere (3),
When reducing the air flow from the tuyere (3) in the blast furnace (1) wind reduction process, the distance to the deepest part (7) of the raceway (6) was measured, and this measured distance was decreasing. In some cases, the blast furnace operating method is characterized in that the amount of pulverized coal blown from the tuyere (3) is reduced or blocked to prevent the raceway (6) from collapsing or shrinking. The race is obtained in advance an upper limit of the required coal blowing amount to maintain way deepest portion a distance to (7), and the upper limit amount based on, reduce the coal blowing amount from the tuyere (3) or blocking The operating method of the blast furnace of Claim 1 characterized by the above-mentioned. The distance to the deepest part (7) of the raceway (6) is
A transmission step (S61) of transmitting a transmission wave that is frequency-modulated toward the deepest portion (7) of the raceway (6) through the tuyere (3);
Receiving step of receiving the deepest part reflected wave generated by reflecting the transmitted wave at the deepest part (7) of the raceway (6) and the non-deepest part reflected wave generated by reflecting at other than the deepest part (7) (S62),
A circularly polarized wave selection step (S63) for selectively removing a predetermined circularly polarized wave included in each reflected wave obtained in the reception step (S62);
A beat wave generating step (S64) for generating a beat wave by superimposing the output of the circularly polarized wave selecting step (S63) and the transmission wave;
A band removing step (S65) for removing the non-deepest part reflected wave included in the beat wave;
Fourier transform processing step (S66) for Fourier transforming the output of the band removal step (S65) to derive a frequency spectrum;
The blast furnace operating method according to claim 1 or 2 , characterized in that the blast furnace is obtained through a distance calculating step (S67) for calculating a distance from the distribution of the frequency spectrum to the raceway deepest portion (7). In the circularly polarized wave selection step (S63), the transmission wave is a circularly polarized wave deflected in a certain direction, and is deflected in the direction opposite to the transmission wave from the reflected wave obtained in the reception step (S62). 4. The method for operating a blast furnace according to claim 3 , wherein a circularly polarized wave is extracted. In the band removing step (S65), the frequency component of the non-deepest part reflected wave is estimated in advance, and the frequency component is removed from the beat wave by a band removing filter that removes only the frequency component. A method for operating a blast furnace according to claim 3 or 4 . The blast furnace operating method according to any one of claims 3 to 5 , wherein the distance calculating step (S67) calculates a distance by the following formula based on a distribution of a frequency spectrum of beat waves.

Here, l: distance between tuyere and raceway deepest part, t: round-trip time of transmission wave, T: period, fb: beat wave frequency, F: frequency modulation width, c: speed of transmission wave. The blast furnace operating method according to claim 3 , wherein the transmission wave is a microwave.

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