JPH04167962A - Method for continuously measuring molten iron level for pouring mixer car - Google Patents

Abstract

PURPOSE:To accurately measure molten iron level regardless of surroundings by executing frequency-analyse to beat signal generated at a mixer and treating. CONSTITUTION:Microwave executing FM modulation by adding signal from modulation circuit 10 to transmitting circuit 11 of the microwave is divided into the one transmitted to the mixer 12 through a root A and the one transmitted to a circulator 13 - transmitter/receiver antenna 14 - circulater 13 - mixer 12 through a root B. The beat signal is generated at the mixer 12 and amplified in an amplification circuit and transmitted to a high velocity Fourier transformer 26 and the beat signal is divided into each frequency composition. The signal from the high velocity Fourier transformer 26 is displayed on a display 28, after discriminating shifting signal by operating difference between two or more Fourier transformed signals at the time, when the molten iron surface differs, with a processor 27 and treating so as to come to the actual measured distance signal.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method of measuring the ever-changing level of hot metal injected into a pig iron mixer using microwaves.

[Conventional technology]

A summary of the distance measurement method using conventional microwaves is given in Part 3.
As shown in the figure, the microwave frequency-modulated by the modulation circuit 10 and transmitted from the transmitting circuit 11 enters the mixer 12 through path A, and the microwave which enters the mixer 12 through path B.
Through the circulator 13 → transmitting/receiving antenna 14 →
It is branched from the circulator 13 to the mixer 12. Here, the lengths of paths A and B are respectively! 1.2
2, the distance from the transmitting/receiving antenna 14 to the measurement surface 15 is R, and the propagation time tl, L! of the microwave to the mixer through path A and path B! Then, the propagation time of the microwave to the mixer is as follows.

t,=1. /C Moe=　C1t+2R)/to Here, C is the luminous flux.

The frequency of the microwave is linearly modulated as shown in Figure 4,
If the modulation width is ΔF and the turning time is τe, then
The microwaves passing through paths A and B cause a frequency shift in a part of the mixer and generate a beat wave, but the frequency r of this beat wave is equal to the frequency difference between the two microwaves, and the following equation can be obtained. Are known.

f, = (ΔF/Te) /2,
Since the distance can be measured, the above processing is processed by the signal processing unit 16 to generate an output signal.

When measuring, for example, the level of hot metal in a pig iron mixer car using this microwave, a microwave antenna 18 is provided on the top of the pig iron mixer car 17 as shown in FIG. The emitted microwaves are emitted from the antenna 18 at a relatively narrow angle, and the reflected waves are sent again to the processing device to process the hot metal 19 using the processing method described above.
was measuring the level of

In the figure, 20 is a cooling box, 21 is a heat shield plate, 22 is an air inlet, 23 is an inclined gutter through which hot metal flows, and 24 is an operation panel.

[Problems to be Solved by the Invention] However, when measuring the level of hot metal in the pig iron mixing car 17 using microwaves, the received microwaves are not all reflected waves from the hot metal 19 but other waves. Since there is also a reflected wave from a fixed object, other reflected components are also mixed, so it has various beat components.

Therefore, distance calculations are currently performed by sampling the most normal and stable beat waveforms of the various beat components mentioned above, but there are cases where stable reflected waves reflected from surrounding fixed objects are sampled. In this case, there is a problem that erroneous measurements may occur.

The present invention has been made in view of the above circumstances, and provides a method for continuously measuring the level of hot metal injected into a mixed pig iron car, which can measure the level of moving hot metal using microwaves without causing erroneous measurements. The purpose is to provide.

[Means for Solving the Problems] A method for continuously measuring the level of hot metal injected into a pig iron mixer according to the present invention in accordance with the above-mentioned object transmits frequency-modulated microwaves to the hot metal that is the object to be measured while receiving pig iron in a pig iron mixer car. In a method for continuously measuring the level of hot metal injected into a pig iron mixing car, in which the distance is measured by a beat signal of the transmitted wave and the reflected wave from the hot metal that changes every moment, the frequency of the beat signal is analyzed and the beat wave that changes every moment is selected. It is configured such that the measured signal is obtained by using the measured signal.

(Function) In the method for continuously measuring the level of hot metal injected into a pig iron car as described in claim 1, since the frequency of the beat signal of the transmitted wave and the reflected wave from the hot metal that is the object to be measured is analyzed, In addition to the beat signals generated by reflected waves from the hot metal, even if there are beat signals caused by reflected waves from surrounding fixed objects, they become fixed signals if frequency analyzed.

On the other hand, since the object to be measured changes from moment to moment, if frequency analysis is performed, the frequency will change from moment to moment in accordance with the distance, and it can be distinguished from the above-mentioned fixed signal.

Therefore, by using a signal whose frequency changes with the passage of time as a measurement value, the distance to the surface to be measured can be measured without erroneous measurement.

[Example] Next, a method embodying the present invention will be described with reference to the attached drawings to provide an understanding of the present invention.

As shown in FIG. 1, a signal from a modulation circuit 10 is applied to a microwave transmission circuit 11 to generate an FM-modulated microwave. This microwave enters the mixer 12 through path A, and the other through path B from circulator 13 to transmitting/receiving antenna 14 to circulator 13 to mixer 1.
2, the beat signal is generated by the mixer 12 as described above, and the frequency of the beat signal is as follows.

rl-(ΔF/Te) X (Lx tl) However,
t,=1. /CLx”=(41!z+2R)/CC=3X
10" cm /sec ΔF = Microwave modulation width Te = Return time Therefore, if there is an object around that reflects microwaves, a beat wave will be generated due to the reflection from that object, but, If it is a fixed object, its frequency will be constant.

On the other hand, if the object to be measured is a liquid level such as hot metal in a pig iron mixing car,
The liquid level will change depending on the amount of hot metal that is introduced.

Therefore, the signal from the mixer 12 is amplified by an amplifier circuit 25 and applied to a fast Fourier transformer 26. As a result, the beat signal is decomposed into each frequency component, and this situation is shown in FIG.

Note that the transmitting/receiving antenna 14 uses a narrow directional antenna with a directivity angle of about 2.1 degrees, and there is no object other than the object to be measured in the microwave transmission direction.

Therefore, the beat signal S caused by the object to be measured becomes thick (becomes thick), and the beat signal N caused by reflection from other surrounding objects
becomes smaller, but the beat signal S moves left and right depending on the increase and decrease of the molten pig iron on the surface to be measured.

Since the configuration of the fast Fourier transformer 26 is well known, a detailed explanation will be omitted, but the signal to be processed is passed through an anti-aliasing filter, A/D converted at a predetermined sample timing, stored in memory, and then calculated. The device performs Fourier transform to analyze and output each frequency component of the beat signal.

Therefore, by calculating the distance using the beat signal that moves left and right as an output signal, the level of the molten pig iron that moves up and down can be measured.

Therefore, the signal from the fast Fourier transformer 26 is processed as described above in the processing device 27. , the moving signal is discriminated, processed to be a distance signal to be actually measured, and displayed on the display 28.

〔Effect of the invention〕

As is clear from the above explanation, the method for continuously measuring the level of hot metal injected into a pig iron mixer according to the present invention processes the beat signal generated by the mixer by frequency analysis, so that reflected signals from surrounding fixed objects are eliminated. removed and can accurately measure the level of hot metal regardless of the surrounding environment.

[Brief explanation of the drawing]

Fig. 1 is a schematic block diagram for explaining the method of the present invention, Fig. 2 is a graph showing a frequency-analyzed beat signal, and Fig. 3 is a graph showing a frequency-analyzed beat signal.
The figure is a schematic block diagram of a measuring method according to a conventional example, FIG. 4 is a waveform diagram of the same, and FIG. 5 is a schematic side view showing a measurement situation of the hot metal surface of a pig iron mixing car. [Explanation of symbols] 10- - Modulation circuit, 11-.--1 Transmission circuit, 1
2- Mixer, 13---- Circulator-114-1 Transmitting/receiving antenna, 15--1 Measurement surface (hot metal surface), 25----- Amplifier, 26-----
- fast Fourier transformer, 27--processing device, 2
8------ Display

Claims (1)

[Claims] A pig iron mixing car injection method in which frequency-modulated microwaves are transmitted toward the hot metal that is the object to be measured during pig iron receiving, and the distance is measured by the beat signal of the transmitted waves and the ever-changing reflected waves from the hot metal. A method for continuously measuring the level of hot metal injected into a mixing wheel, characterized in that the frequency of the beat signal is analyzed, and a constantly changing beat wave is selected as a measurement signal.