JP2016197019A - Level gauge, and level measuring method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable the absolute level of slag in a blowing converter furnace to be measured on a real time basis unaffected by noise from unnecessary reflected waves from the furnace throat.SOLUTION: A level gauge is equipped with a microwave emitter that sweeps frequencies and emits a microwave; an antenna unit that is arranged in an aperture part positioned on the throat side of a converter furnace, radiates a microwave toward inside of the furnace and receives the microwave reflected by the slag face; a detector that detects the received reflected wave; an antenna drive mechanism that at least adjusts the arranged angle of the antenna unit; and an arithmetic processor that calculates the level of the slag face from the emitted microwave and the detected reflected wave. The arithmetic processor calculates, after performing filtration to pass only higher frequencies than a frequency corresponding to the throat position relative to the difference frequency signal between the transmitted and reflected microwaves, a waveform regarding the distance between the antenna unit and the slag position on the basis of the frequency spectrum obtained from Fourier transform of the difference frequency signal and determines the peak position to be the position of the slag face.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a level meter and a level measurement method.

  In order to improve productivity in the converter steelmaking process, it is important to shorten the time required for blowing by increasing the acid feed rate. However, increasing the acid delivery rate not only causes slapping and spitting, leading to a decrease in yield, but also causes problems such as adhesion of bullion and slag to the furnace mouth and hood, etc. there is a possibility.

  Therefore, in order to improve productivity, it is important to measure the level of the contents of the converter and to grasp the slag forming behavior that is a sign of slopping in real time accurately. Therefore, conventionally, a method for measuring the bath surface level of the melt charged in the converter has been devised. For example, as shown in the following Patent Documents 1 to 3, the level of a radar system using a microwave A total has been proposed.

JP-A-3-281716 JP-A-3-281717 JP 2012-107304 A

  However, in the methods described in Patent Document 1 and Patent Document 2, it is necessary to insert a microwave transmitter / receiver into the furnace through the sublance hole. Measurement of slag forming behavior in the second half of smelting and detection of predicting slopping cannot be performed. Further, it is necessary to provide a large water cooling mechanism, purge mechanism or insertion drive mechanism with the distance meter mounted, which causes a problem in terms of space and cost. In addition, a large amount of hot metal and slag is scattered in the converter and slag and ground iron adhere to the front surface of the transmitter / receiver (antenna). Therefore, it is necessary to increase the frequency of maintenance, and slag and ground iron are scattered heavily. In some cases, it may be difficult to continuously measure the level during one charge.

  In addition, the method described in the above-mentioned Patent Document 3 installs a microwave transmitter / receiver in the upper part of the sublance hole, so that the level measurement in the latter half of the blowing using the sublance cannot be performed, and the slag forming behavior measurement in the latter half of the blowing Cannot detect signs of slapping or slipping. Also, if the converter operation continues to be charged several times, the furnace mouth becomes narrower due to the attached metal, but when transmitting microwaves from the transceiver to install the microwave transceiver vertically downward Unnecessary reflected waves from the furnace mouth are generated, and it is difficult to accurately measure only the reflected signal from the surface of the slag.

  Therefore, the present invention has been made in view of the above problems, and the object of the present invention is to attach the absolute level of slag in the converter during blowing to the furnace port in real time. An object of the present invention is to provide a level meter and a level measurement method capable of reducing and measuring noise due to unnecessary reflected waves from a bare metal whose amount of adhesion varies.

In order to solve the above-described problem, according to one aspect of the present invention, a level meter that measures the level of a slag surface in a converter using a microwave, the microwave sweeps the frequency and emits the microwave. The microwave injection unit and the opening located on the furnace port side of the converter are arranged to irradiate the microwave toward the inside of the converter and to reflect the microwave reflected by the slag surface. A receiving antenna unit; a detecting unit that detects a reflected wave of the microwave received by the antenna unit; an antenna driving mechanism that adjusts at least an arrangement angle of the antenna unit in the opening; and the microwave emitting unit An arithmetic processing unit that calculates the level of the slag surface based on the microwave emitted by the detection unit and the reflected wave of the microwave detected by the detection unit, and the arithmetic processing unit After performing the frequency filtering process on the difference frequency signal between the reflected wave of the microwave and the transmission wave of the microwave irradiated toward the inside of the converter, After the Fourier transform of the difference frequency signal to generate a spectrum related to the frequency, a waveform relating to the distance between the antenna unit and the position of the slag is calculated, and the peak position in the waveform is set as the position of the slag surface. ,
The frequency filtering process is a process in which a high-pass filter that passes only a frequency higher than the frequency of the difference frequency signal corresponding to the position of the furnace port of the converter is applied to the difference frequency signal, and the slag surface Prior to the measurement, the antenna unit performs transmission and reception of the microwave while the arrangement angle is changed by the antenna driving mechanism, and the arithmetic processing unit corresponds to the position of the furnace opening of the converter. A level meter is provided for identifying the frequency of the difference frequency signal.

  The arithmetic processing unit further performs a process of passing a frequency lower than the frequency of the difference frequency signal corresponding to the position of the furnace bottom of the converter as the frequency filtering process, and at the position of the furnace opening of the converter. A band pass filter that allows only a frequency band defined by the frequency of the difference frequency signal corresponding to the position of the bottom of the converter from the frequency of the corresponding difference frequency signal to act on the difference frequency signal, The antenna unit performs transmission and reception of the microwave while the arrangement angle is changed by the antenna driving mechanism in a state in which no melt exists in the converter, and the arithmetic processing unit further performs a recording operation. The frequency of the difference frequency signal corresponding to the position of the furnace bottom of the furnace may be specified.

  The cut-off frequency of the high-pass filter is preferably a frequency represented by (the peak frequency of the difference frequency signal corresponding to the furnace port position of the converter + the full width at half maximum of the peak frequency).

  The pass band of the bandpass filter is equal to or greater than (the peak frequency of the difference frequency signal corresponding to the position of the furnace port of the converter + the full width at half maximum of the peak frequency of the furnace port), at the position of the bottom of the converter. It is preferable that the frequency band is defined by the peak frequency of the corresponding difference frequency signal minus the full width at half maximum of the peak frequency of the furnace bottom.

  The arithmetic processing unit may dynamically change a frequency characteristic of a filter used for the frequency filtering process according to detection of a peak corresponding to a predetermined position of the converter in the difference frequency signal.

  In the state where the melt is present inside the converter, the antenna unit has an axis indicating the irradiation direction of the microwave irradiated toward the inside of the converter. Inclined with respect to the furnace wall of the converter, and the microwave is irradiated to both the surface of the slag and the side wall of the lance or the furnace wall of the converter by the antenna driving mechanism. The arrangement angle is preferably controlled.

  The antenna unit has a value (d / r) obtained by dividing a distance d from an irradiation center of the microwave on the slag surface to a side wall of the lance or a furnace wall of the converter by an irradiation radius r of the microwave. It is preferable to control to be within a predetermined range.

  The antenna section is controlled in such a manner that a part of the microwave is further reflected by the side wall of the lance, and the value of (d / r) is more than −0.66 and less than 0.66. There may be.

  The arrangement angle of the antenna unit is controlled so that a part of the microwave is further reflected by the furnace wall of the converter, and the value of (d / r) is more than −1.7 and 1.7. It may be less.

  The antenna section has an arrangement angle such that 20 to 70% of the microwave power irradiated toward the inside of the converter is supplied to the side wall of the lance or the furnace wall of the converter. Preferably it is controlled.

  Preferably, the arithmetic processing unit spatially averages the calculated waveform along the distance, and then sets a peak position in the averaged waveform as the slag position.

  The arithmetic processing unit may generate a trend chart in which the information on the determined position of the slag is temporally averaged and the position of the slag is associated with the elapsed time of the process in the converter. Good.

  The response speed of measurement is preferably 30 milliseconds or less.

  In order to solve the above-mentioned problem, according to another aspect of the present invention, there is provided a level measurement method for measuring a level of a slag surface in a converter using a microwave, prior to the measurement of the slag surface. And / or in a state where no melt is present inside the converter, the microwave is radiated by sweeping the frequency from the antenna portion disposed in the opening located on the furnace port side of the converter. Then, the reflected wave of the microwave from the converter side is received by the antenna unit, and a difference frequency signal between the detected reflected wave of the microwave and the transmitted wave of the irradiated microwave is obtained. The frequency corresponding to the furnace port position of the converter is specified, and in the state where the melt exists in the converter, the frequency is swept from the antenna unit and irradiated with microwaves, and the slag surface Receive the microwave reflected by the antenna unit The frequency corresponding to the furnace mouth position of the converter with respect to the difference frequency signal between the detected reflected wave of the microwave and the transmission wave of the microwave irradiated toward the inside of the converter A frequency filtering process that allows only higher frequencies to pass, and a Fourier transform is performed on the difference frequency signal after the frequency filtering process to generate a spectrum related to the frequency, and then between the antenna unit and the position of the slug. A waveform related to the distance is calculated, the peak position in the waveform is set as the position of the slag surface, and the frequency filtering process passes only a frequency higher than the frequency of the difference frequency signal corresponding to the position of the furnace port of the converter. A high-pass filter that acts on the difference frequency signal, and prior to the measurement of the slag surface, the antenna unit, A level measurement method is provided in which the microwave is transmitted and received while the arrangement angle is changed by the antenna driving mechanism, and the frequency of the difference frequency signal corresponding to the position of the furnace port of the converter is specified. .

  As described above, according to the present invention, it is possible to measure the absolute level of slag in the converter during blowing in real time and reduce noise caused by unnecessary reflected waves from the furnace port. .

It is explanatory drawing which showed typically the structure of the level meter which concerns on embodiment of this invention. It is explanatory drawing for demonstrating the principle of the level meter using a microwave. It is explanatory drawing for demonstrating the installation method of the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the magnitude | size of the irradiation area | region of a microwave. It is explanatory drawing for demonstrating the magnitude | size of the irradiation area | region of a microwave. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on the same embodiment. It is the block diagram which showed an example of the structure of the arithmetic processing unit with which the level meter which concerns on the same embodiment is provided. It is explanatory drawing for demonstrating the arithmetic processing in the arithmetic processing unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the arithmetic processing in the arithmetic processing unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the arithmetic processing in the arithmetic processing unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the arithmetic processing in the arithmetic processing unit which concerns on the same embodiment. It is explanatory drawing for demonstrating the arithmetic processing in the arithmetic processing unit which concerns on the same embodiment. It is the flowchart which showed an example of the flow of the level measurement method which concerns on the embodiment. It is the block diagram which showed an example of the hardware constitutions of the arithmetic processing unit which concerns on embodiment of this invention. 10 is a graph showing the results of Experimental Example 1. FIG. 10 is a graph showing the results of Experimental Example 1. FIG.

  Exemplary embodiments of the present invention will be described below in detail with reference to the accompanying drawings. In addition, in this specification and drawing, about the component which has the substantially same function structure, duplication description is abbreviate | omitted by attaching | subjecting the same code | symbol.

(About the structure of the level meter)
First, the configuration of the level meter according to the embodiment of the present invention will be described with reference to FIG. FIG. 1 is an explanatory diagram schematically showing an example of the configuration of the level meter according to the present embodiment.

  The level meter 10 according to the present embodiment uses a slag as a measurement object S in a melt (molten metal, molten steel, or slag) existing in a converter, and the position of the surface of the slag (also referred to as a slag surface) is micro. It is a device that measures by waves. Here, the position of the slag surface is referred to as a slag surface level (separation distance D in FIG. 1, hereinafter also referred to as a slag level). As shown in FIG. 1, the level meter 10 includes a microwave irradiation unit 100, an antenna drive mechanism 150, and an arithmetic processing unit 200.

  The microwave irradiation unit 100 is a unit that sweeps the frequency of the measurement object S and irradiates the measurement object S with microwaves, and detects a reflected wave of the microwave from the measurement object S. The detailed configuration of the microwave irradiation unit 100 will be described in detail below.

  The antenna drive mechanism 150 is a drive mechanism that adjusts at least the antenna arrangement angle of the microwave irradiation unit 100. By operating the antenna driving mechanism 150, the antenna arrangement angle in the microwave irradiation unit 100 changes, and the microwave can be irradiated in a desired direction. The antenna driving mechanism 150 can use a known driving mechanism such as an actuator.

  The antenna driving mechanism 150 can adjust various installation conditions in order to change the antenna arrangement state in addition to the antenna arrangement angle of the microwave irradiation unit 100.

  The arrangement position of the antenna driving mechanism 150 is not particularly limited, and the antenna driving mechanism 150 is installed at an arbitrary position as long as it can act on the antenna of the microwave irradiation unit 100. It is possible.

  The arithmetic processing unit 200 is a unit that calculates the absolute level of the slag, which is the measurement object S, using the signal data related to the microwave detected by the microwave irradiation unit 100. Details of the arithmetic processing unit 200 will also be described in detail below.

<Configuration of microwave irradiation unit>
Next, the configuration of the microwave irradiation unit 100 according to the present embodiment will be described in detail with reference to FIG.

  The microwave irradiation unit 100 according to the present embodiment is realized as a unit adopting, for example, a frequency modulated continuous wave (FM-CW) system. As shown in FIG. 1, the microwave irradiation unit 100 includes a frequency sweeper 101 and an oscillator 103, which are examples of a microwave emitting unit, a directional coupler 105, an antenna 107 that functions as an antenna unit, and a mixer. 109 and a detector 111 functioning as a detection unit.

  The frequency sweeper 101 is a device that changes the frequency continuously and linearly by controlling the frequency of microwaves oscillated from an oscillator 103 described later. The frequency modulation width and the modulation period may be adjusted in advance so that the microwave can be emitted and detected with a desired accuracy. Further, the frequency sweeper 101 to be used is not particularly limited, and a known one may be used.

  The oscillator 103 is a device that oscillates a microwave having a frequency specified by the frequency sweeper 101 under the control of the frequency sweeper 101. The frequency (center frequency) oscillated by the oscillator 103 will be described in detail below. Further, the intensity of the oscillated microwave is not particularly limited, but an appropriate intensity may be selected in accordance with the size of the rough separation distance to the measurement object. A microwave that sweeps and emits a frequency oscillated from the oscillator 103 is output to a directional coupler 105 described later, and a part thereof is output to a mixer 109 described later. Note that a known oscillator can be used as the oscillator 103 to be used. However, in order to realize real-time measurement of the slag level, a device having a response speed that can easily follow the frequency sweep by the frequency sweeper 101 is used. It is preferable to use it.

  The directional coupler 105 guides the microwave oscillated from the oscillator 103 to an antenna 107 described later, and transmits the microwave received by the antenna 107 (that is, the reflected microwave from the measurement object S) described later. This is a device that guides to the mixer 109. The directional coupler 105 is not particularly limited, and a publicly known one can be used.

  The antenna 107 functions as a microwave transceiver, which irradiates the measurement object S with the microwave emitted from the oscillator 103 and receives the reflected wave from the measurement object S. In the microwave irradiation unit 100 according to the present embodiment, the antenna 107 is installed in an opening existing above the furnace port of the converter, as will be described later. Therefore, the size of the antenna 107 is preferably set so as to be compatible with the opening. The shape of the antenna 107 is not particularly limited. For example, it is preferable to use a Cassegrain type or horn type antenna. In order to improve the directivity of the microwave radiated from the antenna 107, a lens made of a dielectric such as Teflon may be attached to the tip of the antenna 107 or the like.

  Further, the antenna 107 has an arrangement angle to the opening controlled by the antenna driving mechanism 150, irradiates microwaves in an arbitrary direction, and receives reflected waves from various parts of the measurement object S. It becomes possible.

  The mixer 109 mixes the microwave (that is, the transmission wave) emitted from the oscillator 103 and the reflected microwave (that is, the reception wave) from the measurement object S that is guided from the directional coupler 105. And it outputs to the detector 111 of a back | latter stage.

  The detector 111 is a device that detects a synchronization signal between the signal generated by mixing the transmission wave and the reception wave by the mixer 109 and the frequency modulation. By such detection processing by the detector 111, the reflected microwave received by the antenna 107 is detected. A detection signal detected by the detector 111 is output to the arithmetic processing unit 200. As for the detector 111, it is preferable to verify the magnitude of the reflected wave from the measurement object S in advance and use a detector that can detect a signal with desired accuracy and response speed.

[Principle of microwave rangefinder]
The microwave irradiation unit 100 having such a configuration functions as a so-called microwave rangefinder. Hereinafter, the principle of the FM-CW type microwave rangefinder will be briefly described with reference to FIG. explain.

  Now, as shown in the uppermost part of FIG. 2, the frequency modulation width of the oscillator 103 controlled by the frequency sweeper 101 is set to F [Hz], and the modulation period is set to T [seconds]. And As shown in the uppermost part of FIG. 2, the frequency of the transmission wave changes continuously and linearly with time.

  On the other hand, the received wave reflected by the measurement object S and received by the antenna 107 causes a delay Δt [second] proportional to the separation distance D to the measurement object S. As a result, there is a frequency difference Δf [Hz] corresponding to the separation distance D between the transmission wave and the reception wave at the same time. When such a transmission wave and reception wave are mixed by the mixer 109, a difference frequency signal (beat wave) having a frequency component corresponding to Δf is obtained.

  Now, the time delay Δt between the transmission wave and the reception wave corresponds to the time required for the microwave to reciprocate between the antenna 107 and the measurement object S. Further, since the propagation speed of the microwave is the speed of light c, the time delay Δt can be expressed by the following expression 101. On the other hand, the relationship represented by the following expression 102 is established between the frequency Δf of the beat wave and the time delay Δt. Therefore, it can be understood that the separation distance D can be calculated by the following equation 103 by using the equations 101 and 102. As is apparent from Equation 103, the process of calculating the separation distance D is equivalent to calculating the frequency of the beat wave shown in FIG.

  Here, in an actual measurement environment, the beat wave generated by the mixer 109 is rarely a sine wave as shown in FIG. 2, and may be a composite wave in which a number of frequency components are mixed. Many. Therefore, when obtaining the frequency of the beat wave composed of such a plurality of frequency components, digital signal processing is performed by the arithmetic processing unit 200 described later.

  Specifically, a beat wave composed of a plurality of frequency components is Fourier-transformed to generate a spectrum with the horizontal axis as the frequency [Hz], and the horizontal axis is further converted into a distance [m] by the above equation 103. A waveform as shown in the lower part of FIG. 2 (hereinafter also referred to as “distance waveform”) is generated with the vertical axis as the intensity. In this distance waveform, the position of the horizontal axis that gives the main peak is the separation distance D to be obtained.

[How to install antenna 107]
Now, a method of installing the microwave irradiation unit 100 on the measurement object S (more specifically, a method of installing the antenna 107) based on the above principle will be described in detail with reference to FIG. FIG. 3 is an explanatory diagram for explaining a method of installing the microwave irradiation unit according to the present embodiment.

  The measurement object S of the level meter 10 according to the present embodiment is a slag surface existing inside a converter used in a steelmaking process, as shown in the left side of FIG. In the converter steelmaking process, hot metal is charged into the converter as shown in FIG. 3 and oxygen is blown into the hot metal from the main lance to adjust the hot metal components to produce molten steel. Slag is generated on the surface of the melt as the treatment proceeds.

  Further, in the process performed in the converter, steam, dust, and the like are generated. Therefore, a hood for preventing the generated dust and the like from being exposed to the external environment is provided near the furnace port of the converter. The hood is provided with an opening for inserting the main lance into the converter and an opening (ie, a sub lance hole) for inserting the sub lance into the converter.

  The antenna 107 of the microwave irradiation unit 100 according to the present embodiment is installed in an opening such as a sublance hole located on the furnace port side of the converter as shown in the right side of FIG. As described above, the antenna drive mechanism 150 is disposed in the vicinity of the antenna 107, and the antenna 107 can be disposed at a different angle by operating the antenna drive mechanism 150.

  In the microwave irradiation unit 100 according to the present embodiment, when an iron melt exists in the converter and the slag surface is measured, as shown in FIG. The axis (the axis connecting the center of the antenna and the center of the irradiation area on the slag surface) indicating the direction of microwave irradiation is inclined with respect to the side wall of the lance inserted into the converter. The arrangement angle of the antenna 107 may be controlled so that both the surface of the slag and the side wall of the lance are irradiated. The antenna 107 has an axis indicating the microwave irradiation direction inclined with respect to the furnace wall of the converter, not the lance side wall, and the microwave is applied to both the surface of the slag and the furnace wall of the converter. The arrangement angle may be controlled so as to be irradiated.

  In this embodiment, the angle of the antenna 107 when measuring the surface of the slag is microscopic with respect to both the surface of the slag and the sidewall of the lance, or both the surface of the slag and the furnace wall of the converter. The arrangement angle of the antenna 107 may be controlled in the direction in which the microwave is irradiated only on the surface of the slag, without being limited to the direction in which the wave is irradiated.

  Further, in the present embodiment, the installation location of the antenna 107 is not limited to the sub lance hole, and a dedicated opening is newly provided at the position of the hood capable of facing the inside of the converter (slag surface). The antenna 107 may be installed in the new opening.

  Next, the characteristics of the antenna 107 will be briefly described with reference to FIGS. 4A and 4B. 4A and 4B are explanatory diagrams for explaining the size of the microwave irradiation region.

  As schematically shown in FIG. 4A, the microwave irradiated from the antenna 107 is diffused in a range defined by the diffusion angle α, which is one of the characteristics of the antenna 107, while being measured with respect to the measurement object S. Irradiated. Here, when the diameter of the antenna 107 (antenna diameter) is φ1, and a general distance to the slag surface is 8 to 22 m in a general converter, the separation distance D is the maximum separation distance. Consider how the size of the microwave irradiation region (diameter of irradiation region) φ2 at the position of D = 22 m changes.

  The minimum diffusion angle of the microwave irradiated from the antenna is defined by the diameter φ1 of the antenna and the frequency of the microwave. Here, since the antenna 107 according to the present embodiment is installed in a place having a limited size such as an opening, the antenna diameter φ1 is limited. For example, the size of the opening is limited to about 300 to 400 mm at most because of the restriction that a large opening cannot be provided in the hood in order to prevent dust and the like from leaking outside. Therefore, the diameter of the antenna 107 is, for example, about 250 to 275 mm when the size of the opening is 300 mm.

  In this case, when the frequency of the irradiated microwave is 10 GHz and the antenna diameter φ1 is 250 mm, as shown in FIG. 4B, the irradiation region at the position of D = 22 m which is the maximum separation distance. The diameter φ2 is about 3 m. The diameter φ2 of the irradiation region becomes smaller as the frequency of the microwave used is increased, and is about 1.5 m when using a 24 GHz microwave, 0.9 m when using a 39 GHz microwave, and 48 GHz. Is 0.7 m when using a microwave of 0.3 mm and 0.3 m when using a 94 GHz microwave.

  Here, if the diameter φ2 of the irradiation region becomes too large, the intensity of the microwave irradiated from the antenna 107 is also dispersed, and a sufficient intensity of the reflected wave cannot be obtained. In addition, when microwaves diffuse widely (in other words, when the diffusion angle α is large), the reflected wave from the furnace mouth or hood located about 7 m from the antenna 107 becomes a noise component, and the measurement sensitivity is remarkably increased. In addition to the reduction, the intensity of the microwave that enters the converter also decreases as the noise component increases. In addition, if the number of times the converter is used increases, the diameter of the furnace port becomes narrow due to adhesion of metal or slag to the furnace port, and when the diffusion angle α is large, a part of the microwave is shielded by the furnace port. It can also happen. For the reasons described above, in order to maintain the intensity of the microwave supplied to the irradiation region within a preferable range, a frequency of 24 GHz or more that can reduce the diameter φ2 of the irradiation region to less than 1.5 m is used. Is preferred.

  In addition, by using the microwave irradiation unit 100 according to the present embodiment in a state where there is no iron melt inside the converter, it is also possible to measure the distance to various parts of the converter. . Hereinafter, with reference to FIG. 5, control of the antenna installation state, which is performed in a state where no iron melt exists in the converter, will be described in detail. FIG. 5 is an explanatory diagram for describing a microwave irradiation method in the microwave irradiation unit according to the present embodiment.

  As schematically shown in the left diagram of FIG. 5, prior to measurement of the slag surface, such as before and after blowing, the antenna driving mechanism 150 is operated so that the microwave is irradiated toward the furnace port. By controlling the disposition angle of 107, it is possible to measure the separation distance to the furnace mouth or the slag attached to the furnace mouth. Further, as schematically shown in the right diagram of FIG. 5, the antenna drive mechanism 150 is operated in a state where there is no iron melt inside the converter, and microwaves are irradiated toward the furnace bottom. Thus, by controlling the arrangement angle of the antenna 107, it is possible to measure the separation distance to the furnace bottom.

  The measurement of the separation distance to the furnace opening and the bottom of the furnace can be performed by continuously operating the antenna driving mechanism 150 and continuously changing the installation angle of the antenna 107 within a certain angle range. is there.

  Note that the measurement of the separation distance to the furnace mouth or the metal bar attached to the furnace mouth can be performed before and after blowing as described above for each charge of the converter. Needless to say, the present invention may be carried out in the presence of an iron melt. Moreover, since the adhesion amount of the metal which adheres to a furnace port changes every moment, it is preferable to carry out frequently.

  Thus, by operating the antenna drive mechanism 150 and controlling the arrangement angle of the antenna 107, microwaves are irradiated in an arbitrary direction, and reflected waves from various parts of the measurement object S are emitted. It becomes possible to receive.

  In addition, the utilization method of the measurement result of the separation distance to the furnace opening and the furnace bottom obtained in this way will be described again in detail below.

  Next, the reason for controlling the antenna 107 of the microwave irradiation unit 100 to be tilted when measuring the separation distance to the slag surface will be specifically described with reference to FIGS. 6-8 is explanatory drawing for demonstrating the microwave irradiation method in the microwave irradiation unit which concerns on this embodiment.

  As shown in the diagram on the left side of FIG. 6, the position of the slag surface can be measured by irradiating the microwave downward in the vertical direction. Here, since oxygen gas is vigorously supplied from the main lance during the blowing process, the surface of the slag is depressed around the vicinity of the main lance, and the surface fluctuates violently. Therefore, when the microwave is irradiated downward in the vertical direction as shown in the left diagram of FIG. 6, the traveling direction of the reflected wave of the microwave constantly changes, and the reflected wave of the microwave returns to the antenna 107. The rate of coming may be reduced.

  Also, when the antenna 107 is simply tilted, for example, the surface of the main lance is statistically increased in horizontal level, but when the microwave is irradiated to the slag surface without collecting, There is a case where the rate at which the reflected wave of the microwave returns to the antenna 107 may decrease.

  On the other hand, as shown in the diagram on the right side of FIG. 6, the inventors irradiate the antenna 107 with microwaves obliquely from the antenna 107 so that a part of the microwave is irradiated on the side wall of the lance. It was thought that the ratio of the reflected wave returning to would increase significantly. As a result of studying the reason, the present inventors have come to the conclusion that, as shown in FIG. 7A, a so-called corner cube mirror is artificially realized on the slag surface and the lance side wall. It was.

  The corner cube mirror is a combination of two mirrors (mirrors) at a right angle as shown in FIG. Now, as shown in FIG. 7B, it is assumed that the microwave traveling from the P1 direction is incident on the lower mirror P2 at an incident angle θ. In that case, the microwave is reflected from P2 toward P3 at a reflection angle θ. Here, since the two mirrors are combined at right angles, the reflected wave at P2 is incident on the other mirror at P3 at the incident angle (90-θ) and reflected at the reflection angle (90-θ). . As is clear from the geometric positional relationship shown in FIG. 7B, the straight line P1-P2 and the straight line P3-P4 are parallel to each other, so that the incident wave traveling from P1 eventually enters from P4. It will return in the direction.

  Similarly, it is assumed that the microwave traveling from the P4 direction is incident on the side mirror P3 at an incident angle (90-θ). In that case, the microwave is reflected from P3 toward P2 at a reflection angle (90-θ). Here, since the two mirrors are combined at a right angle, the reflected wave at P3 is incident on the other mirror at the incident angle θ at P2, and is reflected at the reflection angle θ. As a result, the incident wave traveling from P4 returns from P1 toward the incident direction.

At this time, as shown in FIG. 7B, the incident wave and the reflected wave are misaligned by the magnitude D _off .

  As is clear from the geometric positional relationship, the relationship between the incident wave and the reflected wave as described above is the same regardless of whether the wave is incident from any direction, and depends on the incident angle θ. do not do.

  Therefore, as shown in FIG. 7A, the microwave incident on the slag surface is irradiated by the corner cube mirror by irradiating the microwave in an oblique direction so that both the slag surface and the lance sidewall are irradiated. The microwave reflected by the side wall returns to the direction of the antenna 107 (that is, the direction of the opening), and the microwave incident on the lance side wall is reflected by the slag surface and returns to the direction of the antenna 107.

  The corner cube mirror as shown in FIG. 7B can be realized by combining two mirrors at right angles. Therefore, as shown in FIG. 8, a corner cube mirror can also be realized by using the slag surface and the furnace wall of the converter. Therefore, when the furnace opening of the converter is large with respect to the installation position of the antenna 107 and the microwave irradiation direction can be changed relatively freely, as shown in FIG. By irradiating both the slag surface and the microwave, the same effect as described above can be obtained.

  Here, when irradiating both the slag surface and the lance side wall with the microwave, it corresponds to considering the slag position in the vicinity of the main lance as the slag position in the entire converter. Moreover, when irradiating both the slag surface and the furnace wall of a converter with a microwave, it corresponds to considering the position of the slag in the vicinity of the furnace wall of a converter as the slag position in the whole converter.

Now, as shown in FIG. 7B, the traveling direction of the wave represented by P1-P2, and the traveling direction of the wave represented by P3-P4, which occurs positional displacement by an amount D _off. Therefore, it is preferable to determine the degree of inclination of the antenna 107 so that the antenna 107 can receive the offset even if the offset D _off exists.

  Therefore, in the following, the relationship between the degree of inclination of the antenna 107 and the degree of reception of the reflected wave will be described in detail with reference to FIGS. 9A to 10. 9A to 10 are explanatory diagrams for explaining a microwave irradiation method in the microwave irradiation unit according to the present embodiment.

  The relationship between the degree of inclination of the antenna 107 and the degree of reception of the reflected wave can be verified by actually measuring using an actual machine, or using a simulation such as electromagnetic field analysis by a known finite element method. It is also possible to obtain it theoretically. When obtaining the above relationship using simulation, it is assumed that an incident wave having a Gaussian beam shape proceeds from the antenna 107 while diffusing toward the slag surface, and the intensity of the reflected wave returning to the antenna 107 is calculated. That's fine.

  In this case, if it is assumed that there is no reflector that reflects microwaves (that is, a lance side wall or a furnace wall), the corner cube mirror as shown in FIG. The intensity of the reflected wave that travels in the regular reflection direction on the surface and returns to the antenna 107 decreases. Also, assuming that there is a reflector such as a lance side wall or furnace wall, a corner cube mirror as shown in FIG. 7B is realized, and the incident wave returns toward the antenna 107. It becomes. Furthermore, the reception intensity of the reflected wave corresponding to the incident angle θ is changed by fixing the position corresponding to the antenna 107 and changing the incident position of the incident wave on the slag surface, assuming the presence of the reflector. Can understand changes in When the received intensity of the reflected wave is small, the intensity of the beat wave detected by the detector 111 of the microwave irradiation unit 100 becomes small, and the rate at which the measurement ends normally decreases.

  Here, in order to grasp the change in the reception intensity of the reflected wave according to the incident angle θ, the inventors of the present invention have the size of the microwave irradiation region on the slag surface as shown in FIGS. 9A to 9C. Focusing on the relationship between (radius r) and the separation distance d from the center of the microwave dose description to the reflector, a parameter (d / r) obtained by dividing the separation distance d by the irradiation radius r was considered. . Here, the separation distance d is zero at the center of the irradiation region, and the right direction in FIGS. 9A and 9B is a positive value. That is, as shown in FIGS. 9A and 9B, when more than half of the irradiation microwave is applied to the slag, d ≧ 0, and in FIG. 9C, the center of the irradiation region is located on the right side of the reflector. In the case where more than half of the irradiation microwave is irradiated to the lance side wall or the furnace wall, d <0.

  9A and 9C, the absolute value of the separation distance d may be smaller than the irradiation radius r. As shown in FIG. 9B, the absolute value of the separation distance d is the irradiation value. A case where the radius is larger than the radius r is also conceivable.

  Since the position of the opening where the antenna 107 is installed is fixed, the traveling direction of the microwave is changed by changing the value of (d / r), and the reflected wave (return wave) returning to the antenna 107 is returned. Will be shifted. Therefore, according to the characteristics of the antenna 107, the intensity of the microwave returned to the range that the antenna 107 can receive may be measured or simulated.

  Now, using an actual converter, a Cassegrain type antenna (diffusion angle α = 1 degree) with an antenna diameter of 250 mm is installed in the opening provided near the sublance hole, and the center frequency is 45 GHz (modulation width ± 1 GHz, modulation period) An experiment was conducted to measure the signal intensity of the beat wave while changing the value of d / r using a microwave of 50 Hz) (fixed to a certain value with an oscillation output of 100 mW or more). Here, as an evaluation standard, the rate at which beat waves were normally measured at a measurement rate of 50 Hz was referred to as a measurement rate, and changes in the measurement rate were verified. The measurement rate introduced in this verification is a ratio obtained by dividing the time during which a beat wave can be normally measured at least once per second by the total measurement time, as shown in the following formula 110. It is.

Measurement rate [%]
= (Time at which normal measurement was performed at least once / second: [second] / total measurement time [second]) × 100
... (Formula 110)

The obtained results are shown in FIG. In FIG. 10, the horizontal axis is the value of (d / r), and the vertical axis is the measurement rate calculated based on the above formula 110. As is apparent from FIG. 10, it can be seen that an excellent measurement result of a measurement rate of 90% or more was obtained in the range of −0.66 <d / r <0.66. Further, the intensity of the reflected wave returning to the antenna 107 in the range of (d / r) was calculated by the above simulation (electromagnetic field analysis by the finite element method). In the range of (d / r), it was revealed that 20 to 70% of the irradiation area of the microwave irradiated from the antenna was irradiated to the lance side wall. This numerical range is a range in which the pseudo corner cube mirror is effective. For example, in order to satisfy this condition when the lance diameter is 0.4 m, it is required that the irradiation area is (cross-sectional area of the lance / irradiation area of the microwave) ≧ 20%. 0.2 / 0.45) Since ² is approximately 0.2, it was found that the frequency of the microwave is preferably 39 GHz or more at which the diameter of the irradiation area becomes 0.9 m. The upper limit is not symmetrical with 70% because the lance is cylindrical and acts as a convex convex mirror.

  Moreover, since the experiment with the actual machine which irradiates the microwave toward the furnace wall while changing the value of (d / r) could not be performed, the verification when the microwave is irradiated to the furnace wall is The following simulation was performed. Here, the relationship between the intensity of the reflected wave obtained in the irradiation experiment on the lance side wall and the measurement rate is considered to be the same even when the furnace wall is irradiated with microwaves, and the measurement rate is 90%. The range of (d / r) giving the intensity of the reflected wave as described above was calculated by simulation. As a result, when microwaves are applied to both the furnace wall and the slag surface, the measurement rate may be 90% or more by setting −1.7 <d / r <1.7. It became clear.

  The range related to the value of (d / r) is the same numerical range even when the microwave frequency is changed.

  Note that the reason why the range of the value of (d / r) differs between the case of irradiating the microwave toward the furnace wall and the case of irradiating the microwave toward the lance side wall is as follows. This can be considered as a concave mirror, whereas the lance is considered to function as a convex mirror due to its shape.

  The method for installing the antenna 107 in the microwave irradiation unit 100 has been described in detail above with reference to FIGS.

  In the converter steelmaking process, only the bottom blowing is performed before blowing, so the surface of the slag, which is the measurement target, is relatively gentle, but when the blowing is started, a large amount of oxygen is released from the main lance. As a result, the surface fluctuates violently and bubbles are violently generated by the slag oxidation reaction. In such a state, the reflectance of the microwave from the slag surface is reduced, and a higher measurement sensitivity is required as compared with hot metal level measurement before blowing. Therefore, in order to more accurately measure the position of the slag surface even during blowing, it is preferable that the power ratio of the microwave irradiation unit 100 as a whole is 40 dB or more.

  Moreover, the slag surface during blowing swells up and down violently as described above, and may fluctuate by about ± 1 m in 0.5 seconds. Therefore, in order to measure the average surface level, it is important to average the measured results after measuring the instantaneous value by shortening the time constant. At this time, in order to measure the level of the slag surface with an accuracy of 50 mm or less, it is preferable to have a response speed of about 30 milliseconds or less. If the measurement time is longer than this, the fluctuation of the surface leads to a decrease in the peak intensity and an increase in the width of the detection signal, which may reduce the sensitivity. The lower limit of the response speed is not particularly limited, and the faster the response speed, the more the measurement result that follows the actual change in the surface level of the slag can be obtained.

  The configuration of the microwave irradiation unit 100 included in the level meter 10 according to the present embodiment has been described in detail above with reference to FIGS.

<About the configuration of the arithmetic processing unit>
Next, the configuration of the arithmetic processing unit 200 according to the present embodiment will be described in detail with reference to FIG. FIG. 11 is a block diagram illustrating an example of the configuration of the arithmetic processing unit 200.

  The arithmetic processing unit 200 provided in the level meter 10 according to the present embodiment is based on the microwave emitted from the oscillator 103 of the microwave irradiation unit 100 and the reflected microwave detected by the detection unit 111. It is a processing unit that calculates the level of. More specifically, the arithmetic processing unit 200 is a unit that performs digital signal processing on the beat wave detection signal detected by the microwave irradiation unit 100 and calculates the position of the slag surface. The arithmetic processing unit 200 may be mounted as an arithmetic processing chip provided in the microwave irradiation unit 100, provided outside the microwave irradiation unit 100, and acquiring data from the microwave irradiation unit 100. It may be realized as an information processing apparatus such as various computers or servers.

  As shown in FIG. 11, the arithmetic processing unit 200 mainly includes a measurement control unit 201, an arithmetic processing unit 203, a display control unit 205, and a storage unit 207.

  The measurement control unit 201 is realized by a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), a communication device, and the like. The measurement control unit 201 controls the measurement process of the measurement object S by the microwave irradiation unit 100 according to the present embodiment and the adjustment process of the antenna 107 by the antenna drive mechanism 150, respectively.

  More specifically, the measurement control unit 201 outputs a control signal for starting the operation of the microwave irradiation unit 100 when the microwave irradiation unit 100 starts measuring the level position of the measurement object S.

  In addition, the measurement control unit 201 determines the arrangement angle of the antenna 107 of the microwave irradiation unit 100 (for example, the arrangement angle in a plane parallel to the paper surface in the drawing on the right side of FIG. In order to adjust the arrangement angle in a plane perpendicular to the antenna 107, it is also possible to output a control signal for changing the arrangement angle to the antenna driving mechanism 150 provided in the vicinity of the antenna 107. is there. As a result, the user of the level meter 10 according to the present embodiment can confirm the state of the output of the beat wave measured by the microwave irradiation unit 100 (for example, signal intensity, S / N ratio, etc.) The separation distance to the mouth and the bottom of the furnace can be measured, and the most suitable arrangement angle (in other words, the value of d / r) of the antenna 107 in the operation of interest can be adjusted.

  The arithmetic processing unit 203 is realized by, for example, a CPU, a ROM, a RAM, and the like. The arithmetic processing unit 203 performs arithmetic processing for calculating the position of the slag surface in the converter by performing digital signal processing using the beat wave detection signal output from the microwave irradiation unit 100. The arithmetic processing unit 203 can also generate a trend chart in which the calculated position of the slag surface is recorded for each elapsed time of the blowing process in the converter.

  When the arithmetic processing unit 203 calculates various types of information representing the measurement result by the microwave irradiation unit 100 such as the calculated position of the slag surface and the trend chart, the arithmetic processing unit 203 outputs information representing the obtained result to the display control unit 205. . In addition, the arithmetic processing unit 203 outputs information representing the obtained result to an operation management computer or the like for managing the operation by the converter, for example, in the form of a form via an output device such as a printer. It is also possible to output data representing the obtained result.

  Details of the arithmetic processing in the arithmetic processing unit 203 will be described later.

  The display control unit 205 is realized by, for example, a CPU, a ROM, a RAM, an output device, and the like. The display control unit 205 outputs the measurement result related to the position of the slag surface in the converter, which is the measurement object S, transmitted from the arithmetic processing unit 203, an output device such as a display provided in the arithmetic processing unit 200, or the arithmetic processing unit 200. Display control when displaying on an output device or the like provided outside. Thereby, the user of the level meter 10 can grasp the measurement result regarding the position of the slag surface in the converter on the spot.

  The storage unit 207 is realized by, for example, a RAM or a storage device included in the arithmetic processing unit 200 according to the present embodiment. In the storage unit 207, various parameters, intermediate progress of processing, or various databases or programs that need to be saved when the arithmetic processing unit 200 according to the present embodiment performs some processing, or various databases and programs are appropriately stored. To be recorded. The storage unit 207 can be freely read and written by the measurement control unit 201, the arithmetic processing unit 203, the display control unit 205, and the like.

[Operation processing in the processing unit]
Next, the arithmetic processing in the arithmetic processing unit 203 included in the arithmetic processing unit 200 will be described in detail with reference to FIGS. 12-16 is explanatory drawing for demonstrating the arithmetic processing in the arithmetic processing part which concerns on this embodiment.

○ Rough Flow of Arithmetic Processing Performed In the arithmetic processing unit 203 according to this embodiment, a signal indicating the detection result of the beat wave as shown in the uppermost stage of FIG. 12 is output from the microwave irradiation unit 100. First, the obtained signal is A / D converted into digital data. Then, the arithmetic processing unit 203 performs Fourier transform (more specifically, Fast Fourier Transform (FFT)) on the obtained beat wave digital data, as shown in the second row of FIG. A simple spectrum. More specifically, the arithmetic processing unit 203 applies the digital irradiation data of the microwave irradiation unit 100 to the digital data obtained by the fast Fourier transform (the spectrum whose horizontal axis is the beat frequency shown in the second stage of FIG. 12). A distance waveform determined on the basis of the set value (a coefficient represented by (cT / 2F) in the rightmost side of the above-described formula 103) is multiplied to generate a distance waveform as shown in the third row of FIG. In the distance waveform obtained by converting the horizontal axis of the spectrum obtained by the Fourier transform into a distance, the horizontal axis corresponds to the distance between the antenna 107 and the position of the slag surface, and the vertical axis corresponds to the signal intensity.

  Here, since the beat wave detected by the microwave irradiation unit 100 has many irregularities derived from the surface variation of the slag, it is observed as an aggregate of minute peaks as shown in the uppermost stage of FIG. Is done. Therefore, the arithmetic processing unit 203 performs a moving average process of a predetermined length in the distance direction, and spatially averages the obtained distance waveform. As a result, local peaks in the distance waveform before averaging are flattened, and significant peaks are emphasized. In the example shown in FIG. 12, the distance waveform as shown in the third stage of FIG. 12 is spatially averaged, and the averaged distance waveform as shown in the lowermost stage of FIG. 12 is calculated. The

  The length in the distance direction at which the moving average process is performed is not particularly limited, and may be set as appropriate by analyzing past operation data or the like, for example, about 300 to 500 mm. be able to.

  Thereafter, the arithmetic processing unit 203 determines, as the distance to the slag surface, the distance that gives the maximum intensity among the peaks having the intensity equal to or higher than a preset threshold in the distance waveform after spatially averaging. Here, the arithmetic processing unit 203 may use the obtained distance to the slag surface as an absolute level of the slag surface, for example, to another reference such as the height from the bottom of the converter. It may be converted. The threshold value used for such processing is not particularly limited, and may be set as appropriate by analyzing past operation data or the like.

  In addition, the arithmetic processing unit 203 may generate a so-called trend chart in which the obtained distance to the slag surface is associated with the position of the slag surface and the elapsed time of the blowing process in the converter. Such a trend chart is, for example, a graph showing a time-series progress with the elapsed time of the blowing process on the horizontal axis and the level of the obtained slag surface on the vertical axis.

  At this time, in order to cope with the fluctuation caused by the surface fluctuation of the measurement level, the arithmetic processing unit 203 performs a moving average process on the temporal change of the peak with a certain time width, and shows a trend indicating a global level transition. It can be a chart. The size of the temporal moving average process is not particularly limited, but can be set to about 200 milliseconds, for example.

  Furthermore, the arithmetic processing unit 203 performs various statistics such as an average height of the slag surface, a maximum value of the slag surface height, and a minimum value of the slag surface height based on the obtained trend chart. It is good also as a feature-value which calculates quantity and characterizes blowing process.

○ Filtering process By the way, in actual operation, the metal in the furnace becomes attached to the furnace mouth due to the scattered material in the furnace generated by blowing and gradually increases. As a result, the size, height, shape, etc. of the furnace port change, and the measurement range by the microwave becomes narrower. As shown schematically in FIG. 13, in addition to the reflected wave from the slag surface, An excessive reflected wave from the furnace port with gold is detected. As a result, the distance waveform generated by the arithmetic processing unit 203 is superimposed with a peak associated with the reflected wave from the furnace port in addition to the peak related to the slag surface. If the above calculation process is performed using a distance waveform in which a peak due to a reflected wave from the furnace port is superimposed, a measurement error is caused.

  Further, the refractory bricks installed at the bottom of the converter melt down, so that the separation distance from the antenna 107 changes even if the same amount of molten material is charged into the furnace. Therefore, if the arithmetic processing is performed in such a state, a result that the position of the slag surface is lowered is obtained.

  Therefore, the arithmetic processing unit 203 according to the present embodiment uses the information on the separation distance from the antenna 107 to the furnace mouth and the separation distance from the antenna 107 to the furnace bottom to improve the measurement accuracy due to the reflected wave from the furnace mouth. This prevents a decrease in measurement accuracy due to a decrease in the furnace bottom position.

Here, as shown in the above equation 103, the separation distance D is equivalent to the frequency Δf of the difference frequency signal (that is, beat wave) between the irradiated microwave and the reflected wave of the microwave. Therefore, in the arithmetic processing unit 203 according to the present embodiment, the beat wave frequency Δf ₁ corresponding to the separation distance D ₁ from the antenna 107 to the furnace opening and the beat corresponding to the separation distance D ₂ from the antenna 107 to the furnace bottom. Using the wave frequency Δf ₂ , processing for preventing a decrease in measurement accuracy is performed.

In other words, distance D from the antenna 107 to the surface of the slag is greater than distance D ₁ of the up furnace opening, which should be less than the distance D ₂ to the furnace bottom. Therefore, according to the above equation 103, the beat wave frequency Δf corresponding to the position of the slag surface is higher than the frequency Δf ₁ corresponding to the separation distance D ₁ to the furnace port, as schematically shown in FIG. Larger and smaller than the frequency Δf ₂ corresponding to the separation distance D ₂ to the furnace bottom.

  Therefore, in the arithmetic processing unit 203 according to the present embodiment, when the detection result of the beat wave output from the microwave irradiation unit 100 is acquired as illustrated schematically in FIG. 15, Fourier transform is performed on the beat wave. Prior to performing the above, filtering processing based on the frequency as described above is performed. Thereafter, the arithmetic processing unit 203 performs processing such as Fourier transform and slag surface level specification by using the beat wave after the filtering process.

Here, the frequency Δf ₁ of the beat wave corresponding to the separation distance D ₁ is determined by operating the antenna drive mechanism 150 and measuring the separation distance D ₁ to the furnace port before blowing, as described above. Can be identified. The frequency Delta] f ₂ of the beat wave corresponding to the separation distance D ₂ may not operate the antenna driving mechanism 150, measure the distance D ₂ in a state where the melt on the rolling furnace has not been charged to the furnace bottom By doing so, it can be specified. Since the separation distances D ₁ and D ₂ change every moment, it is preferable to measure each time there is an opportunity. By obtaining as accurate separation distances D ₁ and D ₂ as possible, appropriate filtering processing can be performed.

The arithmetic processing unit 203 performs the filtering process as shown in FIGS. 14 and 15 by using the beat wave frequencies Δf ₁ and Δf ₂ specified in advance as described above.

Specifically, the arithmetic processing unit 203 applies a high-pass filter that passes only a frequency component higher than Δf ₁ to the beat wave output from the microwave irradiation unit 100, thereby lowering Δf ₁ or less. The influence of the extra reflected wave having the frequency can be reduced.

Further, the arithmetic processing unit 203 acts on a beat wave with a bandpass filter that passes a frequency higher than Δf ₁ and passes a frequency lower than Δf ₂ instead of the above-described high-pass filter. May be. Thereby, not only the influence of the extra reflected wave having a low frequency of Δf ₁ or less, but also the influence caused by the melting of the refractory brick at the bottom of the furnace that has occurred before blowing can be removed from the beat wave.

Now, consider a case where two peaks A and B that are close to each other as shown in FIG. 16 exist on the frequency spectrum such as the beat wave. At this time, whether peak A and peak B can be separated depends on the relationship between the peak frequency of peak A and peak B and the full width at half maximum (FWHM) of peak A. Judgment can be made based on whether or not That is, as schematically shown in FIG. 16, the peak frequency of the peak A _{f a,} the full width at half maximum of the peak A FWHM, the peak frequency of the peak B when expressed as _{f b, f b ≧ f a} + FWHM If the relationship is satisfied, peak A and peak B can be separated. Therefore, also in the high-pass filter and the band-pass filter used in the filtering processing according to the present embodiment, the cutoff frequency of the high-pass filter and the pass band of the band-pass filter are determined by paying attention to the spectral resolution as described above. It is preferable.

That is, the cutoff frequency of the high-pass filter according to the present embodiment, based on the spectral resolution as described above, (peak frequency Delta] f 1 ₊ peak frequency of the difference frequency signal corresponding to the position D ₁ of the furnace opening of the converter Delta] f ₁ The full width at half maximum) is preferable. Further, the pass band of the band-pass filter according to the present embodiment, (full width at half maximum of the peak frequency Delta] f ₁ of the peak frequency Delta] f 1 ₊ furnace opening of the difference frequency signal corresponding to the position D ₁ of the furnace opening of the converter) or more, it is preferable that the frequency band defined by the following _- (furnace bottom of the full width at half maximum of the peak frequency Delta] f ₂ hearth difference frequency signal corresponding to the position D ₂ of the peak frequency Delta] f 2 of the converter).

  Further, the arithmetic processing unit 203 according to the present embodiment may treat the frequency characteristics of the filter in the filtering process as described above as static in the blowing process between one charge or several charges, It may be changed dynamically during smelting.

That is, in the arithmetic processing unit 203 according to the present embodiment, when a peak corresponding to the difference frequency Δf ₁ or Δf ₂ is detected from a certain point during blowing, the metal at the furnace port is detected. The frequency characteristics of the filter may be dynamically changed by determining that the adhesion of the refractory or the refractory bricks at the bottom of the furnace has become noticeable. However, there may be a case where a peak corresponding to the difference frequency Δf ₁ or Δf ₂ is detected as sudden noise. Therefore, when the arithmetic processing unit 203 is continuously detected from the moment when there is a peak having the frequency as described above, the adhesion of the metal at the furnace mouth or the refractory brick at the furnace bottom. Therefore, the frequency characteristic of the filter may be changed so as not to pass the difference frequency corresponding to the furnace opening or the furnace bottom. On the other hand, when a peak having a frequency as described above is detected only at a certain moment and is not detected thereafter, it is determined that noise is superimposed and the frequency characteristics of the filter are not changed.

  The arithmetic processing in the arithmetic processing unit 203 has been described above with reference to FIGS.

  Heretofore, an example of the function of the arithmetic processing unit 200 according to the present embodiment has been shown. Each component described above may be configured using a general-purpose member or circuit, or may be configured by hardware specialized for the function of each component. In addition, the CPU or the like may perform all functions of each component. Therefore, it is possible to appropriately change the configuration to be used according to the technical level at the time of carrying out the present embodiment.

  Note that a computer program for realizing each function of the arithmetic processing unit according to the present embodiment as described above can be produced and installed in a personal computer or the like. In addition, a computer-readable recording medium storing such a computer program can be provided. The recording medium is, for example, a magnetic disk, an optical disk, a magneto-optical disk, a flash memory, or the like. Further, the above computer program may be distributed via a network, for example, without using a recording medium.

  As described above, the level meter 10 according to the present embodiment irradiates the microwave, which has been conventionally irradiated vertically downward from the sublance hole, from the level measurement hole in the measurement process of the slag surface during blowing. To do. Further, the antenna drive mechanism 150 adjusts the antenna 107 to an arbitrary angle, and only the beat wave corresponding to the separation position from the furnace port to the furnace bottom is extracted by the filtering process. In the level meter 10 according to the present embodiment, by performing these processes, the level of the slag surface is measured over the entire blowing while reducing the change in the shape of the furnace port and the influence of the scattered matter on the furnace port. It becomes possible. As a result, it becomes possible to add a sedative agent at an appropriate timing and to grasp the effect of the added sedative agent, and to effectively prevent slopping. Further, by using the level meter 10 according to the present embodiment, the forming state can be controlled to a certain height, and the yield can be improved. Moreover, in the level meter 10 according to the present embodiment, the microwave irradiation unit 100 is not inserted into the converter, and an antenna is installed in an opening provided above the furnace port of the converter. Maintenance is also extremely easy.

  The level meter 10 according to the present embodiment has been described in detail above with reference to FIGS.

(About level measurement method)
Next, a flow of a level measurement method performed by the level meter 10 according to the present embodiment will be briefly described with reference to FIG. FIG. 17 is a flowchart showing an example of the flow of the level measurement method according to the present embodiment.

  In the level meter 10 according to the present embodiment, first, the microwave irradiation unit 100 and the antenna drive mechanism 150 are operated to irradiate microwaves to the furnace port and the furnace bottom (step S101). As a result, the difference frequency signal between the microwave reflected from the furnace mouth and the irradiated microwave (ie, beat wave), or the difference frequency signal between the microwave reflected from the furnace bottom and the irradiated microwave ( A beat wave is detected (step S103). The microwave irradiation unit 100 outputs a signal corresponding to the obtained beat wave to the arithmetic processing unit 200.

The arithmetic processing unit 203 of the arithmetic processing unit 200 performs A / D conversion on the signal corresponding to the beat wave output from the microwave irradiation unit 100 (step S105), and generates digital data of the beat wave. . Thereafter, the arithmetic processing unit 203 performs Fourier transform on the digital data of the beat wave, and specifies the difference frequencies Δf ₁ and Δf ₂ that give peaks corresponding to the furnace opening and the furnace bottom (step S107).

  Next, the microwave irradiation unit 100 and the antenna drive mechanism 150 are operated, and the microwave is irradiated to the inside of the converter (step S109), and the reflected wave of the microwave from the surface of the slag that is the measurement object is irradiated. A difference frequency signal (beat wave) from the microwave is detected (step S111). The microwave irradiation unit 100 outputs a signal corresponding to the obtained beat wave to the arithmetic processing unit 200.

The arithmetic processing unit 203 of the arithmetic processing unit 200 performs a filtering process on the signal corresponding to the beat wave output from the microwave irradiation unit 100 based on the previously determined difference frequencies Δf ₁ and Δf ₂ (step S113). ). Thereafter, the arithmetic processing unit 203 performs A / D conversion on the beat wave after the filtering process (step S115), and generates digital data of the beat wave. Subsequently, the arithmetic processing unit 203 generates a spectrum related to frequency by Fourier transforming the digital data of the beat wave, and calculates a distance waveform by multiplying the obtained conversion result by a distance coefficient (step S117).

  Subsequently, the arithmetic processing unit 203 spatially averages the obtained distance waveform (step S119), and then calculates a distance that gives the maximum peak among peaks having an intensity equal to or greater than a predetermined threshold to the slag surface. The distance is specified (step S121).

  In addition, the arithmetic processing unit 203 performs time averaging on the obtained distance to the slag surface by moving average processing with a certain time width (step S123), and then generates a trend chart (step S125). Next, the arithmetic processing unit 203 calculates various feature amounts such as an average level, a maximum level, a minimum level, and the like of the slag surface using the obtained trend chart (step S127). Thereafter, the arithmetic processing unit 203 outputs the obtained result (step S129).

  The example of the flow of the level measurement method according to the present embodiment has been briefly described above with reference to FIG.

(About hardware configuration)
Next, the hardware configuration of the arithmetic processing unit 200 according to the embodiment of the present invention will be described in detail with reference to FIG. FIG. 18 is a block diagram for explaining a hardware configuration of the arithmetic processing unit 200 according to the embodiment of the present invention.

  The arithmetic processing unit 200 mainly includes a CPU 901, a ROM 903, and a RAM 905. The arithmetic processing unit 200 further includes a bus 907, an input device 909, an output device 911, a storage device 913, a drive 915, a connection port 917, and a communication device 919.

  The CPU 901 functions as an arithmetic processing device and a control device, and controls all or a part of the operation in the arithmetic processing unit 200 according to various programs recorded in the ROM 903, RAM 905, storage device 913, or removable recording medium 921. The ROM 903 stores programs used by the CPU 901, calculation parameters, and the like. The RAM 905 primarily stores programs used by the CPU 901, parameters that change as appropriate during execution of the programs, and the like. These are connected to each other by a bus 907 constituted by an internal bus such as a CPU bus.

  The bus 907 is connected to an external bus such as a PCI (Peripheral Component Interconnect / Interface) bus via a bridge.

  The input device 909 is an operation unit operated by the user, such as a mouse, a keyboard, a touch panel, a button, a switch, and a lever. The input device 909 may be, for example, remote control means (so-called remote controller) using infrared rays or other radio waves, or may be an external connection device 923 such as a PDA corresponding to the operation of the arithmetic processing unit 200. May be. Furthermore, the input device 909 includes, for example, an input control circuit that generates an input signal based on information input by a user using the operation unit and outputs the input signal to the CPU 901. The user of the arithmetic processing unit 200 can input various data and instruct processing operations to the arithmetic processing unit 200 by operating the input device 909.

  The output device 911 is configured by a device that can notify the user of the acquired information visually or audibly. Examples of such devices include CRT display devices, liquid crystal display devices, plasma display devices, EL display devices and display devices such as lamps, audio output devices such as speakers and headphones, printer devices, mobile phones, and facsimiles. The output device 911 outputs results obtained by various processes performed by the arithmetic processing unit 200, for example. Specifically, the display device displays the results obtained by various processes performed by the arithmetic processing unit 200 as text or images. On the other hand, the audio output device converts an audio signal composed of reproduced audio data, acoustic data, and the like into an analog signal and outputs the analog signal.

  The storage device 913 is a data storage device configured as an example of a storage unit of the arithmetic processing unit 200. The storage device 913 includes, for example, a magnetic storage device such as an HDD (Hard Disk Drive), a semiconductor storage device, an optical storage device, or a magneto-optical storage device. The storage device 913 stores programs executed by the CPU 901, various data, various data acquired from the outside, and the like.

  The drive 915 is a recording medium reader / writer, and is built in or externally attached to the arithmetic processing unit 200. The drive 915 reads information recorded on a removable recording medium 921 such as a mounted magnetic disk, optical disk, magneto-optical disk, or semiconductor memory, and outputs the information to the RAM 905. The drive 915 can also write a record on a removable recording medium 921 such as a magnetic disk, an optical disk, a magneto-optical disk, or a semiconductor memory. The removable recording medium 921 is, for example, a CD medium, a DVD medium, a Blu-ray (registered trademark) medium, or the like. The removable recording medium 921 may be a CompactFlash (registered trademark) (CompactFlash: CF), a flash memory, an SD memory card (Secure Digital memory card), or the like. Further, the removable recording medium 921 may be, for example, an IC card (Integrated Circuit card) on which a non-contact IC chip is mounted, an electronic device, or the like.

  The connection port 917 is a port for directly connecting a device to the arithmetic processing unit 200. Examples of the connection port 917 include a USB (Universal Serial Bus) port, an IEEE 1394 port, a SCSI (Small Computer System Interface) port, and an RS-232C port. By connecting the external connection device 923 to the connection port 917, the arithmetic processing unit 200 acquires various data directly from the external connection device 923 or provides various data to the external connection device 923.

  The communication device 919 is a communication interface configured with, for example, a communication device for connecting to the communication network 925. The communication device 919 is, for example, a communication card for wired or wireless LAN (Local Area Network), Bluetooth (registered trademark), or WUSB (Wireless USB). The communication device 919 may be a router for optical communication, a router for ADSL (Asymmetric Digital Subscriber Line), or a modem for various communication. The communication device 919 can transmit and receive signals and the like according to a predetermined protocol such as TCP / IP, for example, with the Internet and other communication devices. The communication network 925 connected to the communication device 919 is configured by a wired or wireless network, and may be, for example, the Internet, a home LAN, infrared communication, radio wave communication, satellite communication, or the like. .

  Heretofore, an example of the hardware configuration capable of realizing the function of the arithmetic processing unit 200 according to the embodiment of the present invention has been shown. Each component described above may be configured using a general-purpose member, or may be configured by hardware specialized for the function of each component. Therefore, it is possible to change the hardware configuration to be used as appropriate according to the technical level at the time of carrying out this embodiment.

  Hereinafter, the level meter and the level measurement method according to the embodiment of the present invention will be specifically described with reference to examples. The examples shown below are merely examples of the level meter and the level measurement method according to the embodiment of the present invention, and the level meter and the level measurement method according to the embodiment of the present invention are limited to the examples shown below. Is not to be done.

  In the present embodiment, an actual operation performed in a converter using an FM-CW unit using a microwave with a center frequency of 45 GHz and a modulation width of ± 1 GHz as the microwave irradiation unit 100. Was measured. The antenna 107 was a Cassegrain type or horn type antenna having an antenna diameter of 250 mmφ. In such an antenna 107, the diffusion angle is 1 degree or less. As the oscillator 103, an oscillation circuit having a frequency of 7.5 GHz multiplied by 6 was used. The oscillation output of the microwave irradiated from the microwave irradiation unit 100 is 100 mW or more, and the modulation period is 50 Hz.

  Prior to blowing, the actuator provided as the antenna drive mechanism 150 was operated to irradiate the furnace opening and the furnace bottom with microwaves.

  The oscillated microwave was partly distributed to the detector 111 side by the directional coupler (or distributor) 105, and the rest was radiated from the antenna 107 to the atmosphere. Of the microwaves reflected by the measurement object, only the component in the direction toward the microwave irradiation unit 100 is collected by the antenna 107, passes through the directional coupler 105, and then mixed with the branched wave by the mixer 109 to be detected. The wave was detected by the device 111. A synchronization signal of the difference frequency component (beat signal) of the mixed signal and the frequency modulation is input to an A / D conversion board of a computer provided outside the microwave irradiation unit 100, and is taken into the computer as digital data. It was.

The beat signal input to the computer was subjected to FFT processing, and the difference frequencies Δf ₁ and Δf ₂ corresponding to the positions of the furnace port and the furnace bottom were specified. Based on the obtained difference frequency, the filter characteristic of the band-pass filter that passes only the component having the frequency between the difference frequencies Δf ₁ and Δf ₂ was determined.

  Thereafter, simultaneously with the start of blowing, the actuator provided as the antenna drive mechanism 150 was operated to irradiate the inside of the converter with microwaves.

  The oscillated microwave was partly distributed to the detector 111 side by the directional coupler (or distributor) 105 in the same manner as described above, and the rest was radiated from the antenna 107 to the atmosphere. Of the microwaves reflected by the measurement object, only the component in the direction toward the microwave irradiation unit 100 is collected by the antenna 107, passes through the directional coupler 105, and then mixed with the branched wave by the mixer 109 to be detected. The wave was detected by the device 111. A frequency filtering process based on the identified frequency (more specifically, a filtering process using a bandpass filter) was performed on the difference signal component (beat signal) of the mixed signal and the synchronization signal of the frequency modulation. Thereafter, the obtained synchronization signal after the filtering process was input to an A / D conversion board of a computer provided outside the microwave irradiation unit 100, and taken into the computer as digital data.

  The beat signal input to the computer is subjected to FFT processing to generate a frequency spectrum, multiplied by the distance coefficient, and then converted into a waveform whose distance is plotted on the horizontal axis to obtain a distance waveform. At this time, a moving average process of about 300 to 500 mm in the distance direction was performed to flatten the local peak, and the peak having the maximum intensity among the peaks equal to or higher than a preset threshold was detected as the surface level of the slag. After that, the peak change over time was subjected to a moving average process with a time width of about 200 milliseconds to obtain the trend chart shown in FIG. 19A. For comparison, a trend chart when no frequency filtering processing is performed is generated and shown in FIG. 19B. In FIG. 19A and FIG. 19B, the black line represents the peak position of the distance waveform that is not subjected to the moving average process, and the white line represents the peak position of the distance waveform after the moving average process.

  As is clear from FIG. 19A, in the obtained trend chart, the transition of the slag level in the converter can be grasped in real time. By using such a trend chart, in the blowing operation, it was possible to increase the amount of acid sent at the initial stage of blowing to promote forming and to take an action of adding a sedative when the level reached a certain value. In addition, by using such a trend chart, the surface level of the slag can be grasped in real time, including surface fluctuations in a short time, so fine control of the lance height and the amount of oxygen can be controlled, and spitting is suppressed. Yield improvement and slipping prevention are now possible.

  On the other hand, in FIG. 19B in which the filtering process is not performed, it is understood that a large number of reflected waves from the furnace port are detected due to the influence of the metal that has adhered to the furnace port, and the measured value varies greatly. In FIG. 19A, the slag level is increased to about 9 m after about 280 seconds from the start of blowing, but in FIG. 19B, the slag level after about 280 seconds from the start of blowing is about 10 m, It can be seen that a measurement error of about 1 m has occurred.

  As is clear from a comparison between FIG. 19A and FIG. 19B, it was found that the level measurement of the slag surface with reduced measurement error can be performed by performing an appropriate filtering process on the detected beat wave. .

  The preferred embodiments of the present invention have been described in detail above with reference to the accompanying drawings, but the present invention is not limited to such examples. It is obvious that a person having ordinary knowledge in the technical field to which the present invention pertains can come up with various changes or modifications within the scope of the technical idea described in the claims. Of course, it is understood that these also belong to the technical scope of the present invention.

DESCRIPTION OF SYMBOLS 10 Level meter 100 Microwave irradiation unit 101 Frequency sweeper 103 Oscillator 105 Directional coupler 107 Antenna 109 Mixer 111 Detector 150 Antenna drive mechanism 200 Arithmetic processing unit 201 Measurement control unit 203 Arithmetic processing unit 205 Display control unit 207 Storage unit

Claims (14)

A level meter that measures the level of the slag surface in the converter using microwaves,
A microwave emission unit that sweeps the frequency and emits the microwave;
An antenna unit that is disposed in an opening located on the furnace port side of the converter, irradiates the microwave toward the inside of the converter, and receives the microwave reflected by the slag surface; ,
A detection unit for detecting a reflected wave of the microwave received by the antenna unit;
An antenna driving mechanism for adjusting at least an arrangement angle in the opening of the antenna unit;
An arithmetic processing unit that calculates a level of the slag surface based on a microwave emitted by the microwave emitting unit and a reflected wave of the microwave detected by the detection unit;
With
The arithmetic processing unit includes:
After performing the frequency filtering process on the difference frequency signal between the detected reflected wave of the microwave and the transmission wave of the microwave irradiated toward the inside of the converter, after the frequency filtering process A frequency-related spectrum is generated by performing a Fourier transform on the difference frequency signal, a waveform relating to a distance between the antenna unit and the slag position is calculated, and a peak position in the waveform is determined as a position of the slag surface. age,
The frequency filtering process is a process in which a high-pass filter that allows only a frequency higher than the frequency of the difference frequency signal corresponding to the position of the furnace port of the converter to act on the difference frequency signal,
Prior to the measurement of the slag surface, the antenna unit performs transmission and reception of the microwave while the arrangement angle is changed by the antenna driving mechanism, and the arithmetic processing unit is positioned at a furnace port of the converter. A level meter that identifies the frequency of the difference frequency signal corresponding to. The arithmetic processing unit further performs a process of passing a frequency lower than the frequency of the difference frequency signal corresponding to the position of the furnace bottom of the converter as the frequency filtering process, and at the position of the furnace opening of the converter. A band pass filter that passes only the frequency band defined by the frequency of the difference frequency signal corresponding to the position of the bottom of the converter from the frequency of the corresponding difference frequency signal, acts on the difference frequency signal;
In a state where there is no melt in the converter, the antenna unit performs transmission and reception of the microwave while the arrangement angle is changed by the antenna driving mechanism, and the arithmetic processing unit further includes: The level meter according to claim 1, wherein a frequency of the difference frequency signal corresponding to a position of a bottom of a converter is specified.   The cut-off frequency of the high-pass filter is a frequency represented by (a peak frequency of a difference frequency signal corresponding to a furnace port position of the converter + a full width at half maximum of the peak frequency). Level meter.   The pass band of the bandpass filter is equal to or greater than (the peak frequency of the difference frequency signal corresponding to the position of the furnace port of the converter + the full width at half maximum of the peak frequency of the furnace port), at the position of the bottom of the converter. 4. The level meter according to claim 2, wherein the level meter is a frequency band defined by a peak frequency of a corresponding difference frequency signal−a full width at half maximum of a peak frequency of the furnace bottom).   The said arithmetic processing part changes dynamically the frequency characteristic of the filter used for the said frequency filtering process according to the detection of the peak corresponding to the predetermined position of the said converter in the said difference frequency signal. 5. The level meter according to any one of 4 above. In the state where the melt exists in the converter,
The antenna section is inclined with respect to the side wall of the lance inserted into the converter or the furnace wall of the converter, and the axis indicating the irradiation direction of the microwave irradiated toward the inside of the converter, and The arrangement angle is controlled by the antenna driving mechanism so that the microwave is irradiated to both the surface of the slag and the side wall of the lance or the furnace wall of the converter. The level meter according to any one of the items.   The antenna unit has a value (d / r) obtained by dividing a distance d from an irradiation center of the microwave on the slag surface to a side wall of the lance or a furnace wall of the converter by an irradiation radius r of the microwave. The level meter according to claim 6, wherein the level meter is controlled to be within a predetermined range.   The antenna section is controlled in such a manner that a part of the microwave is further reflected by the side wall of the lance, and the value of (d / r) is more than −0.66 and less than 0.66. The level meter according to claim 7.   The arrangement angle of the antenna unit is controlled so that a part of the microwave is further reflected by the furnace wall of the converter, and the value of (d / r) is more than −1.7 and 1.7. The level meter according to claim 7, which is less than 10.   The antenna section has an arrangement angle such that 20 to 70% of the microwave power irradiated toward the inside of the converter is supplied to the side wall of the lance or the furnace wall of the converter. The level meter according to any one of claims 6 to 9, which is controlled. The arithmetic processing unit includes:
The level meter according to any one of claims 1 to 10, wherein after the calculated waveform is spatially averaged along the distance, a peak position in the waveform after averaging is set as the position of the slag. .   The arithmetic processing unit generates a trend chart in which the information on the determined position of the slag is temporally averaged, and associates the position of the slag with the elapsed time of processing in the converter. Item 12. The level meter according to Item 11.   The level meter according to any one of claims 1 to 12, wherein a response speed of measurement is 30 milliseconds or less. A level measurement method for measuring the level of a slag surface in a converter using a microwave,
Prior to the measurement of the slag surface and / or in the absence of a melt in the converter, the frequency is swept from the antenna unit disposed in the opening located on the furnace port side of the converter. Then, the microwave is irradiated, and the reflected wave of the microwave from the converter side is received by the antenna unit,
Using the difference frequency signal between the detected reflected wave of the detected microwave and the transmitted wave of the irradiated microwave, the frequency corresponding to the furnace mouth position of the converter is identified,
In the state where the melt is present in the converter, the microwave is swept from the antenna unit and irradiated with the microwave, and the microwave reflected by the slag surface is received by the antenna unit,
For the difference frequency signal between the detected reflected wave of the microwave and the transmitted wave of the microwave irradiated toward the inside of the converter, the frequency corresponding to the furnace port position of the converter Apply frequency filtering to pass only high frequencies,
The Fourier transform is performed on the difference frequency signal after the frequency filtering process to generate a spectrum relating to the frequency, and then a waveform relating to the distance between the antenna unit and the slag position is calculated, and a peak position in the waveform is calculated. The position of the slag surface;
The frequency filtering process is a process in which a high-pass filter that allows only a frequency higher than the frequency of the difference frequency signal corresponding to the position of the furnace port of the converter to act on the difference frequency signal,
Prior to the measurement of the slag surface, the antenna unit transmits and receives the microwave while the arrangement angle is changed by the antenna driving mechanism, and the difference frequency corresponding to the position of the furnace port of the converter. A level measurement method that identifies the frequency of a signal.

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