JPS6157875A - Microwave range measuring instrument - Google Patents

Abstract

PURPOSE:To measure the molten iron level in a torpedo car with simple constitution by detecting the beat signal due to the mixing of a transmitted and a received wave on which frequency modulation is imposed, and determining a slag level and slag thickness from its frequency and amplitude and then determining the molten iron level. CONSTITUTION:A microwave generating circuit 3 receives a modulation signal from a modulation signal generating circuit 1 and radiates a frequency- modulated microwave to a measurement surface from an antenna 2, and its reflected wave is received by the circuit 3, which detects a beat signal whose frequency fb satisfies an equation by mixing the transmitted and received waves. Then, a range arithmetic circuit 5 calculates the distance R1 from the antenna 2 to a slag surface from the synchronism of the beat signal and a beat signal amplitude detecting circuit 6 and a slag layer thickness arithmetic circuit 7 calculates the slag layer thickness according to the amplitude of beat signal. A molten iron level arithmetic circuit 8 measures the molten iron level in the torpedo car from both calculated values with the simple constitution. In the equation, A and B are constants and C is light speed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a microwave distance measuring device used for measuring the level of received pig iron in a torpedo car during pretreatment of hot metal in a blast furnace casthouse.

[Prior art]

A method for correcting measurement errors caused by propagation delays in the coating when a coating such as powder is present on the surface of the molten metal is disclosed in Japanese Patent Laid-open No. 44279/1983 entitled "Displacement Measuring Apparatus". This method uses a microwave interferometer, and the reflection signal from the molten steel surface can be sufficiently detected in a coating with a low dielectric constant, that is, good microwave transmittance, and a relatively thin layer. It was effective.

However, the slag generated by hot metal pretreatment as described here has a high dielectric constant and a thick slag layer, so the components that pass through the slag layer and reach the hot metal surface are reflected at the slag surface. It was found that the molten metal level was sufficiently small compared to the reflected component, and the above method could not accurately measure the level of hot metal.

Figure 4 shows an example of measurement carried out without making any corrections in the above method (the broken line is the estimated hot metal level, the solid line is the level meter output, and the line is the slag layer thickness). This figure shows the situation when the injection of hot metal into the slag was stopped and the thickness of the slag layer gradually decreased. If the received signal is due to the hot metal surface, as the slag layer thickness decreases, the area where the level should rise decreases, indicating that the received signal is due to the slag surface.

In addition, in the above method, in order to detect the received power for correcting the propagation delay in the covering, a branch circuit for detecting the received power, an antenna dedicated to detecting the received power, a wave detector, a power meter, etc. etc., making the equipment, especially the microwave circuit, complicated.

[Purpose of the invention]

An object of the present invention is to measure the level of hot metal in a tobeed car with a relatively simple configuration.
An object of the present invention is to provide a chroma wave distance measuring device.

[Structure of the Invention] FIG. 2 shows the relationship between the slag layer thickness intersection and the amplitude S of the beat signal, which was determined through experiments.As the slag layer thickness increases, the amplitude S of the beat signal decreases. This phenomenon occurs because bubbles containing CO gas, etc. are generated in the slag layer during hot metal 4i11 processing such as desiliconization treatment, and are released into the atmosphere, creating unevenness on the surface.As the thickness of the slag layer increases, the surface The variation in the unevenness becomes larger.

The broken line in FIG. 3 shows the relationship between the unevenness of the slag surface and the beat signal amplitude (relative value), which is expressed by the following equation.

■−÷ −cos4π/a−−−−−(1) However, since the slag surface constantly changes due to the blowing of CO gas, etc., the amplitude V of the beat signal is averaged as shown by the solid line in Figure 3. , which is expressed by the following equation.

V# b/k ----(2) However, b is a constant and there is a proportional relationship between the thickness of the slag layer and the unevenness of the slag surface. , the amplitude V of the beat signal is generally expressed by the following formula (3).
It is expressed as

Therefore, the slag layer thickness can be determined from the amplitude V of the beat signal.

Therefore, the present invention provides a frequency modulation method using FM-opening,
That is, the beat signal obtained by mixing the frequency-modulated transmitted wave and the received wave is detected, the slag level is calculated and derived from the period, and the slag layer thickness is calculated from the relationship between the beat signal amplitude and the slag layer thickness. The molten metal level is calculated and derived from the slag level and slag layer thickness.

〔Example〕

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a block diagram showing an embodiment of the microwave distance measuring device of the present invention. A modulation signal generating circuit generates a modulation signal. The microwave generation circuit 3 receives the modulation signal from the modulation signal generation circuit 1, radiates frequency-modulated microwaves from the antenna 2 toward the surface to be measured, and receives the reflected waves to form the following equation 1. A: Constant R1: Distance from the antenna 2 to the slug surface C: Detect a beat signal with a frequency fb expressed in the speed of light. The amplifier circuit 4 amplifies the beat signal detected by the microwave circuit 3. The beat signal amplified by the amplifier circuit 4 is sent to a distance calculation circuit 5 and a beat signal amplitude detection circuit 6. The distance calculation circuit 5 receives the beat signal and calculates and derives the distance R1 to the slag surface using equation (3). The beat signal amplitude detection circuit 6 detects the averaged amplitude V of the beat signal.

The slag layer thickness calculating circuit 7 receives the output (2) from the beat signal amplitude detecting circuit 6 and calculates and derives the slag layer thickness using equation (3). The molten metal level calculation circuit 8 calculates the distance R1 to the slag surface calculated by the distance calculation circuit 5, the slag layer thickness calculated by the slag layer thickness calculation circuit 7, and the distance from a known reference surface such as the ground to the antenna 2. The molten metal level R is derived from the distance faL using the following formula (5). The molten metal level R determined in this way is output from the output circuit 9.

〔Effect of the invention〕

According to the present invention, it is possible to measure the level of molten metal in a tobbed car, which could not be measured conventionally, with a relatively simple configuration without using a branch circuit for detecting received power or a wattmeter. As a result, it has become possible to secure and control the amount of hot metal regardless of the amount of slag.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing an embodiment of the microwave distance measuring device of the present invention, Figure 2 is a diagram showing the relationship between the slag layer thickness or the amplitude S of the beat signal determined by experiment, and Figure 3 is a diagram showing the relationship between the slag layer thickness and the amplitude S of the beat signal determined by experiment. FIG. 4 is a diagram showing the relationship between the unevenness of the surface unevenness and the amplitude V of the beat signal, and FIG. 4 is a diagram showing a conventional measurement example of molten metal l/bell. 1-Modulation signal generation circuit. 2: Antenna, 3: Microwave circuit. 4: Amplification circuit, 5: Distance calculation circuit. 6: Beat signal amplitude detection circuit. 7: Slag layer thickness calculation circuit. 8: Hot metal level calculation circuit. 9: Output circuit. 1 patentee Nippon Steel Corporation Kuchitetsu Densetsu Kogyo Co., Ltd. Yaskawa Electric Works Co., Ltd.

Claims (1)

[Claims] A microwave distance measuring device for measuring the level of hot metal in a torpedo car with a slag layer formed on the surface of the hot metal, which transmits frequency-modulated microwaves toward the surface to be measured, and transmits the transmitted signal. beat signal detection means for detecting a beat signal obtained by mixing the reflected signal from the surface to be measured; and slag level calculation means for calculating the level of the slag surface from the beat signal detected by the beat signal detection means; A slag layer thickness calculation means for detecting the amplitude of the beat signal and calculating the slag layer thickness, and a means for calculating the molten metal level from the slag level and slag layer thickness respectively obtained by the slag level calculation means and the slag layer thickness calculation means. A microwave distance measuring device comprising: