JP4826239B2 - Method and apparatus for measuring mixture ratio of mixture - Google Patents

Description

  The present invention relates to a mixture mixing ratio measuring method and measuring apparatus, and more particularly to a measuring method and measuring apparatus for a mixing ratio of a blast furnace charging raw material.

  Raw material charging into blast furnaces has traditionally been performed by alternately stacking raw materials such as iron ore, sintered ore, coke, etc. in the furnace in layers, but in recent years, the blast furnace has improved air permeability and iron ore. “Mixing charging” in which iron ore, sintered ore, and coke are mixed in advance on a conveyor before charging and charged into a blast furnace in order to improve the reducibility of stone and sintered ore. The operation method called "" has come to be performed.

  For example, when each raw material is mixed at a predetermined ratio, each raw material is cut out on the conveyor so as to be a predetermined amount from the raw material storage hopper, these raw materials are conveyed by the conveyor, and each raw material is mixed in the surge hopper . Furthermore, the mixed raw material is conveyed from the surge hopper to the blast furnace top by a conveyor, stored in the blast furnace top bunker, and charged into the blast furnace.

In the mixing and charging operation as described above, when the raw material is cut out from the weighing hopper onto the conveyor, the mass ratio of the raw materials of iron ore, sintered ore, and coke is set to a predetermined ratio outside the furnace. The ingredients are mixed. However, when the mixed raw material falls from the conveyor to the surge hopper or furnace bunker and is stored and discharged from there again, the average particle size and specific gravity of each raw material are different. It occurs. In this way, when the raw materials are segregated, the mass ratio of each raw material may not be the correct predetermined ratio when the raw material is charged into the blast furnace, and the mixed charging operation at the predetermined mixing ratio cannot be performed accurately. In some cases, the air permeability inside the blast furnace is lowered, the state of the blast furnace becomes unstable, and the operation efficiency may be lowered. Therefore, if the mixing ratio of each raw material when actually charged in the blast furnace can be measured, such a problem can be dealt with.

As a method for measuring the mixing ratio of raw materials charged in a blast furnace, a method using a magnetic detection element is known (for example, see Patent Document 1). According to this method, the relationship between the mixing ratio of various charges and the output voltage of the magnetic detection element, and the relationship between the output voltage depth from the charge surface and the correction value of the output voltage actually measured by the magnetic detection element. The output voltage value measured with the magnetic detection element in the actual furnace is corrected with a correction value corresponding to the measured depth of the actually measured output voltage value, and the charge mixing ratio is calculated from the corrected output voltage value. It is said that the charge mixing weight ratio in the radial direction of the blast furnace and the depth position thereof can be obtained.
JP-A-56-142809

  However, in the method described in Patent Document 1, it is necessary to install the magnetic detection element at the surface position in the blast furnace where the raw material is charged, and in the state where the raw material frequently falls in the furnace, The mechanical strength of the detection element is required, and sometimes it is affected by the hot air blowing up in the furnace, so thermal strength and stability are also required, and it is difficult to accurately measure the mixing ratio of raw materials. is there. In addition, it is not realistic to always install such a device in a blast furnace from the viewpoint of durability of the device.

  Therefore, the object of the present invention is to solve such problems of the prior art and measure the mixing ratio of the mixture as the raw material to be charged even in an environment where measurement is difficult by a normal method such as in a blast furnace. An object of the present invention is to provide a mixing ratio measuring method and measuring apparatus for a mixture.

The features of the present invention for solving such problems are as follows.
(1) A mixture of a plurality of types of substances having different electromagnetic properties is arranged inside a hollow coil to which an alternating current is applied, or passed in the axial direction of the coil, and an output voltage generated in the coil is measured. A mixture mixing rate measurement method for measuring a mixing rate of substances in the mixture based on the output voltage ,
The coil is composed of an excitation coil and a measurement coil that are arranged in the same axial direction and apply the alternating current,
The alternating current has a plurality of frequencies,
The mixture mixture ratio measurement method, wherein the mixture is arranged inside the exciting coil or passed in the axial direction of the coil, and an output voltage generated in the measuring coil is measured.
(2) the voltage obtained from the measuring coil, divided into in-phase component and its orthogonal component to the alternating current applied to the exciting coil, and calculating the mixing ratio based on the respective values (1 ) The mixture mixing rate measuring method according to.
(3) Below the top bunker of the blast furnace, the coil is installed so that the raw material dropped into the blast furnace passes through the coil, and the mixing ratio of the raw material charged into the blast furnace is measured. (1) or the mixture mixture ratio measuring method according to (2) .
(4) An apparatus for measuring a mixing ratio of substances in a substance to be measured, which is a mixture of a plurality of kinds of substances having different electromagnetic properties,
A hollow coil composed of an excitation coil and a measurement coil arranged in the same axial direction , surrounding or passing through the substance to be measured,
An alternating current power source for applying an alternating current having a plurality of frequencies to the exciting coil;
The substance to be measured is placed inside the coil, or, when passing through the interior, and a voltage measuring device for measuring the output voltage of the measuring coil,
A mixture mixing rate measuring apparatus comprising: a mixing rate calculating device that calculates a mixing rate in the substance to be measured based on the measured output voltage.
(5) the voltage measuring device calculates the in-phase and quadrature components relative to the alternating current of the output voltage of the measuring coil for each of the plurality of frequencies,
The mixture ratio calculation apparatus according to (4) , wherein the mixture ratio calculation device calculates a mixture ratio based on the calculated in-phase component and quadrature component.

  According to the present invention, the mixing ratio of substances in a mixture can be determined easily and accurately. When the present invention is used for measuring the mixing ratio of raw materials charged into a blast furnace, there is no need to operate the sensor part used for measuring the mixing ratio close to the surface of the raw material charged in the furnace, and the charged raw materials It becomes possible to easily determine the mixing ratio of the substances in the inside. For this reason, the mixing rate of the substance in a charging raw material can be controlled correctly, and the operation of a blast furnace is stabilized.

The mixture in which the mixing ratio can be measured in the present invention is a mixture of a plurality of types of substances having different electromagnetic properties. A mixture composed of a plurality of types of substances having different electromagnetic properties is arranged inside a hollow coil to which an alternating current is applied, or the inside of the coil is passed in the axial direction of the coil, and the mixture is arranged in the hollow part of the coil, or By measuring the electromagnetic properties of the mixture as it passes, the mixing ratio of a plurality of types of substances can be detected.
The plurality of types of substances having different electromagnetic properties include various magnetic materials such as ferromagnetic materials and paramagnetic materials, conductors, and combinations thereof. For example, in the case of a blast furnace charge, coke is a conductor. Yes, the sintered ore is a paramagnetic substance, and when passing through the coil, the electromagnetic property of the mixture is measured and detected using the coil, and the mixing ratio can be measured. The electromagnetic properties of the mixture can be detected by measuring the in-phase component of the electromotive force generated in the coil and its quadrature component (component whose phase is shifted by 90 °), that is, the real part and the imaginary part. In this case, a calibration curve is created by measuring the relationship between the mass of the substance and the output voltage independently for each of the multiple types of substances whose mixing ratio is to be measured, and the mixing ratio of the substances in the mixture based on the created calibration curve Is preferably calculated. By creating a calibration curve in advance, the mixing ratio can be easily measured.

  The coil used for measurement can be excitation of the mixture and measurement of electromagnetic properties with one coil (a method in which both the excitation coil and the measurement coil are used), or excitation and measurement can be divided into two coils. This is possible, and it may be properly used depending on the speed of the mixture to be measured (speed 0 when stationary), the position in the coil, the installation space of the coil, the sensitivity of the measuring device, and the like. In addition, when measuring, in order to improve the detection sensitivity in the coil, it is necessary to detect the change component of the electromotive force with high resolution, so that the induced electromotive force induced in the coil is canceled in advance. Therefore, it is preferable to measure the mixing ratio of the mixture.

  When measuring the mixing ratio of the raw materials charged into the blast furnace, install a coil so that the raw materials that fall into the blast furnace and pass through the coil are placed below the top bunker of the blast furnace. Is preferred.

  In order to carry out such a measurement method, an apparatus for measuring a mixing ratio of substances in a substance to be measured, which is a mixture of a plurality of kinds of substances having different electromagnetic properties, the substance to be measured is passed inside. Or a hollow coil that can be placed inside, an AC power source that applies an alternating current to the coil, and when the substance to be measured passes inside the coil or when it is placed in the coil A mixture measuring device comprising: a voltage measuring device for measuring an output voltage of a coil to which alternating current is applied; and a mixing rate calculating device for calculating a mixing rate in a substance to be measured based on the measured output voltage A rate measuring device can be used.

  When the coil is divided into two coils, the coil is composed of an excitation coil and a measurement coil, and the excitation coil is installed on the entry side or the exit side of the substance to be measured in the measurement coil. It is possible to use a mixture mixing rate measuring device characterized in that an alternating current is applied to and the output voltage of the measuring coil is measured.

When measuring the mixing ratio of raw materials charged into the blast furnace, the raw material charged into the blast furnace is passed through the coil below the bunker top bunker, and the mixing ratio of the raw materials charged into the blast furnace is Is preferably measured.
An embodiment in which the present invention is used for measuring the mixing ratio of blast furnace charging raw materials will be described with reference to the drawings. FIG. 1 is a schematic view showing an installation state of a coil for measuring the mixing ratio, which is an embodiment of the measuring apparatus of the present invention. The coil 1 has a hollow core, and the axis 2 of the coil coincides with the direction in which the mixture 3 indicated by an arrow in the figure moves. In the mixture 3, the mixed substances have two different electromagnetic properties. Here, one is a conductor A and the other is a paramagnetic substance B. A mixture 3 of the conductor A and the paramagnetic substance B passes through the inside of the coil 1. At this time, an output is obtained in the coil 1 as a change in the vector sum of the output voltages corresponding to the masses of the conductor A and the paramagnetic substance B. The change in the output of the coil is detected by an impedance measuring device 4 such as an impedance analyzer when the coil is used for both excitation and detection, and by a lock-in amplifier or the like when divided into two, excitation and detection. When using the impedance measuring device, for example, the impedance of the coil when passing the substance at the frequency of interest is measured, and the ratio of the substance is calculated from the change in impedance. At this time, a calibration curve relating to impedance is prepared in advance by the same method as described below, the mass ratio of each substance is obtained from the measured impedance, and the mixing ratio of the conductor A and the paramagnetic substance B is measured. be able to.

  In the conductor A, the response due to the high excitation frequency has a remarkable effect of eddy current, and an actual component corresponding to a change in the electrical resistance of the coil appears. In the paramagnetic material B, the response due to the low frequency excitation frequency has a small effect on the eddy current, and the situation is similar to the presence of an iron core in the coil. Therefore, an imaginary component corresponding to a change in the inductance of the coil. The change of is remarkable. Therefore, it is effective to determine the amount of the paramagnetic material B from the low frequency response and to determine the amount of the conductor A from the high frequency response. These mass ratios are mixing ratios.

  When actually measuring the mixing ratio of the blast furnace raw material, as shown in FIG. 2, a coil 12 (sensor coil) is attached below the furnace top bunker 11 installed in the upper part of the blast furnace 10, and the axis of the coil 12 is Make sure that the raw materials fall in the same direction. A flow rate adjusting gate 13 is installed at the outlet of the furnace top bunker 11, and when the flow rate adjusting gate 13 is opened, the raw material falls, and the output voltage of the coil 12 changes depending on the amount and ratio of the falling raw material. Although there are difficulties in installation and measurement, it is possible to obtain a more accurate mixing ratio by installing the coil 12 on the turning chute 14 and performing measurement in the vicinity of the turning chute.

  As another embodiment of the present invention, the coil is divided into an excitation coil and a measurement coil, the excitation coil is placed in the immediate vicinity of the measurement coil, and a mixture passing through the measurement coil is applied with an AC signal to the excitation coil. A method of exciting can be used. The output of the measurement coil is detected by a lock-in amplifier or the like to detect a change in the output voltage when the mixture passes through the measurement coil.

  In the measurement coil, the induced electromotive force is induced by the magnetic field created by the excitation coil and the measurement accuracy may be poor. In this case, the zero point adjustment of the measurement coil is performed when the raw material does not pass through the coil. Just do it. An example of a measurement circuit in the case of performing zero point adjustment is shown in FIG. In FIG. 3, the excitation coil 15 is connected to a frequency oscillator 16, and excitation is performed by this oscillator 16. The oscillator 16 has outputs of two channels 1Ch16a and 2Ch16b, and the output can output a signal whose phase and amplitude are changed with respect to the signal of 1Ch from the other channel. The oscillator 1Ch16a is connected to the exciting coil 15, and 2Ch16b is connected to the input of the differential amplifier 17. The other input terminal of the differential amplifier 17 is connected to the output of the measuring coil 21, the output of the differential amplifier 17 is input to the lock-in amplifier 18, and the output of the lock-in amplifier 18 is input to the data recording device 19. To be recorded. If it is necessary to process the obtained signal, it is convenient to record amplitude and phase data in the data recording device 19 (computer) through the AD converter 20. The reference signal for the lock-in amplifier 18 uses the excitation signal for the oscillator 16. Further, the cutoff frequency of the low-pass filter of the lock-in amplifier 18 is selected so that it takes a longer time than the raw material passes through the measuring coil 21.

Although a 2ch type oscillator was used, the same effect can be obtained even if adjustment is performed using two oscillators. Further, the voltage induced by the exciting coil 15 to the measuring coil 21 is the signal of the 2ch 16b of the oscillator input to the differential amplifier 17, but it is also conceivable to use a transformer instead of the differential amplifier.
The change in output due to each raw material of the measuring coil 21 is measured in advance in the low frequency and high frequency regions, respectively, and in the case of a blast furnace, it is measured outside the furnace to prepare a calibration curve. Investigate the approximate curve of each calibration curve, assume that the sum of the approximate curves of the real and imaginary parts of the output voltage at each frequency is the detected voltage, substitute the output voltage data into these equations, and solve the simultaneous equations Thus, the mass ratio of each substance can be calculated. Using these calibration curves, the mixing ratio is measured by determining the mass ratio of each substance from the actual component and imaginary component data of the measured coil voltage.

  In general, it is effective to use a frequency band with a remarkable response depending on the type of blast furnace charge (substance in the mixture), but when determining the excitation frequency The frequency is such that the response of each substance shows a sufficiently separable change. For different materials, it is preferable to select an excitation frequency such that the output of the measurement coil 21 measured with the same raw material in the coil included in the same cross-sectional area is 10 times or more that of one material. .

  When the mixing ratio is measured, the excitation coil 15 may be oscillated by superimposing the low-frequency signal and the high-frequency signal. However, if there is room for the installation space of the excitation coil 15, the excitation coil is measured for each measurement frequency. 15 may be installed.

  The mixing ratio of the raw materials charged into the blast furnace from the furnace top was measured using the present invention. An apparatus similar to that shown in FIG. 2 and FIG. 3 was used, and two types of excitation frequencies were used: a low frequency of 10 kHz and a high frequency of 100 kHz. Next, a calibration curve was created for the real component and imaginary segment of the output voltage of the measuring coil at each frequency for the raw materials of coke and sintered ore. 4A is a calibration curve when coke is excited at a low frequency, FIG. 4B is a calibration curve on the low frequency side of the sintered ore, and FIG. 4C is a case where coke is excited at a high frequency. The calibration curve, FIG. 4 (d) is the calibration curve on the high frequency side of the sintered ore. Investigate the detectable range of the measuring coil in the axial direction of the coil, fill the cylindrical space in the coil with a substance, examine the relationship of the coil output to the cross-sectional area occupied in the circle drawn by the coil of the substance, and a calibration curve It was.

  The material dropping speed in the measurement coil portion below the furnace top bunker was calculated, and the cutoff frequency of the low-pass filter of the lock-in amplifier was 1 kHz when the excitation frequency was 10 kHz, and 10 kHz when the excitation frequency was 100 kHz. FIG. 5A shows measured data of the output voltage of the measuring coil when excited at a low frequency, and FIG. 5B shows measured data when excited at a high frequency. FIG. 6 shows the change over time in the ratio of coke and sintered ore, which is the mixing ratio of raw materials obtained from the above results. Further, FIG. 7 shows a flowchart relating to the measurement method.

Schematic which shows one Embodiment of the measuring device of this invention. Schematic which shows one Embodiment at the time of measuring the mixing rate of a blast furnace raw material. The figure which is one Embodiment of this invention, and shows a measurement circuit. (A) Calibration curve when coke is excited at low frequency, (b) Calibration curve when sinter is excited at low frequency, (c) Calibration curve when coke is excited at high frequency, (d) Calibration curve when sinter is excited at high frequency. (A) The graph which shows the actual measurement data of the output voltage of the coil for a measurement at the time of exciting at a low frequency, (b) The graph which shows the actual measurement data at the time of exciting at a high frequency. The graph which shows the time change of the mixing rate of coke and a sintered ore. 5 is a flowchart regarding a measurement method according to the first embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Coil 2 Coil axis | shaft 3 Mixture 10 Blast furnace 11 Furnace top bunker 12 Coil 13 Flow control gate 14 Turning chute 15 Excitation coil 16 Frequency oscillator 16a 1Ch
16b 2Ch
17 Differential Amplifier 18 Lock-in Amplifier 19 Data Recording Device 20 AD Converter 21 Coil for Measurement A Conductor B Paramagnetic Material

Claims (5)

A mixture of a plurality of kinds of substances having different electromagnetic properties is arranged inside a hollow coil to which an alternating current is applied, or is passed in the axial direction of the coil, and an output voltage generated in the coil is measured. A mixture mixing rate measuring method for measuring a mixing rate of substances in the mixture based on
The coil is composed of an excitation coil and a measurement coil that are arranged in the same axial direction and apply the alternating current,
The alternating current has a plurality of frequencies,
The mixture mixture ratio measurement method, wherein the mixture is arranged inside the exciting coil or passed in the axial direction of the coil, and an output voltage generated in the measuring coil is measured. The voltage obtained from the measuring coil, divided into in-phase component and its orthogonal component to the alternating current applied to the exciting coil, according to claim 1, characterized in that for calculating the mixing ratio based on the respective values Method for measuring the mixture ratio. The coil is installed so that the raw material dropped into the blast furnace passes through the coil below the top bunker of the blast furnace, and the mixing ratio of the raw material charged into the blast furnace is measured. The method of measuring a mixture ratio according to claim 1 or 2 . An apparatus for measuring a mixing ratio of substances in a substance to be measured, which is a mixture of plural kinds of substances having different electromagnetic properties,
A hollow coil composed of an excitation coil and a measurement coil arranged in the same axial direction , surrounding or passing through the substance to be measured,
An alternating current power source for applying an alternating current having a plurality of frequencies to the exciting coil;
The substance to be measured is placed inside the coil, or, when passing through the interior, and a voltage measuring device for measuring the output voltage of the measuring coil,
A mixture mixing rate measuring apparatus comprising: a mixing rate calculating device that calculates a mixing rate in the substance to be measured based on the measured output voltage. The voltage measuring device calculates an in-phase component and a quadrature component of the output voltage of the measuring coil with respect to the alternating current for each of the plurality of frequencies;
The said mixture rate calculation apparatus calculates a mixture rate based on the calculated said in-phase component and quadrature component, The mixture mixture rate measuring apparatus of Claim 4 characterized by the above-mentioned.

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