JPS62165110A - Method for measuring level of molten metal - Google Patents

Abstract

PURPOSE:To measure the level of a molten steel with high accuracy with an inexpensive sensor having a simple construction by detecting the erosion condi tion of a cable sensor. CONSTITUTION:The sensor 10 having a length l0 is inserted into a vessel 50 by a feeder 42 and in this stage, a proximity sensor 36 generates output at the point of the time when the front end of the sensor 10 passes in front thereof. The position of the sensor 36 is known and is designated as a reference level L0. The part entering the molten steel 52 is eroded when the sensor 10 enters the molten steel. The erosion is known from the decrease of the sensor length. The insertion length DELTAl0 of the sensor from the level L0 is known by counting 26 the output pulse of a pulse generator 40 from the point of the time when the output is generated in a detection part 34. The erosion length DELTAl1 is deter mined as l0-l1 from the present lengh l1 of the sensor 10 and the level L1 of the molten steel can be determined by making a calculation 28 of DELTAl0-DELTAl1. A rangefinder 44 irradiates laser light on a slag layer 54 and detects the surface position of said layer. The thickness of the layer 54 is determined by calculating 30 the surface position-of the layer 54-the surface L1 of the molten steel.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a level meter for molten metal in a container, and more specifically, to a level meter for molten metal in a container, and more specifically, to a position at the interface between slag and molten metal in a container whose surface is covered with slag. The present invention relates to a method for detecting.

[Conventional technology]

The surface of hot metal is usually covered with a slag layer,
Sometimes it is desired to remove the slag on the surface of the hot metal, and to do this, the hot metal is poured into a container with a discharge port along with the slag.Due to the difference in specific gravity, the hot metal is on the bottom and the slag is on the top, so the slag layer rises due to the injection. There is a method that takes advantage of the fact that it eventually leaves the exhaust port. Of course, in this case, the injection of hot metal must be stopped when the surface of the hot metal in the container rises to the level of the outlet.
Otherwise, hot metal will be discharged from the outlet.

Additionally, it is normal for a slag layer to form on the surface of molten steel tapped from a converter, but this may be adjusted by adding a slag modifier, in which case it is necessary to measure the slag layer thickness. . Measuring the slag layer thickness also requires detection of the interface between the slag layer and molten steel.

[Problem that the invention seeks to solve]

Methods for measuring the level of molten steel in a ladle covered with slag include an equal pressure method that uses the difference in specific gravity between slag and molten steel, and an electrode method that uses the difference in conductivity. The former method involves blowing an inert gas such as nitrogen gas or argon gas into a blowing pipe and gradually lowering the pipe to reach the molten steel level at the point where the back pressure suddenly changes. Check the conductivity between both electrodes while lowering the electrode, detect a sudden change in the conductivity between the electrodes as the electrode tip moves from the slag layer to the molten steel, and determine the molten steel level from the position of the sudden change. However, with the former, there is a problem that the back pressure pulsates due to melting or clogging of the blowing pipe, making it difficult to measure the molten steel level stably.In addition, with the latter, the conductivity between the electrodes decreases due to melting or oxidation of the electrodes. The measurement accuracy is poor. Also, it is easy to get noise.

The present invention aims to provide a method of measuring the level of molten metal such as molten steel with high precision using a sensor having a simple and inexpensive structure without being affected by adverse surrounding environments such as high temperature and dust.

Means for Solving Problem C] The present invention provides a molten metal level measuring method for detecting the interface level between slag and molten metal in a container covered with slag, which includes inserting a sensor into the container. , the position of the tip of the inserted sensor is detected by a proximity sensor, the sensor insertion length ΔRa is measured from the time of detection, and the length β0 of the sensor before insertion into the container and the length of the sensor after insertion are determined by the TDR method. Measure 11 and these lengths! ! o,/! +
The sensor erosion length Δ11 is determined as the difference between the molten metal level L1 and the position of the proximity sensor as Lo, and Ll=
It is characterized by being determined as Lo+ΔRa−Δe+.

[Effect]

In this method, the molten metal level is measured by the damage of the cable sensor, so the measurement is accurate.

In other words, in the method using a blow tube or the method based on the conductivity between two electrodes, it is assumed that the sensor, blow tube, or electrode is normal, but in reality, the object to be measured is at a high temperature, so it melts and breaks down, which introduces errors. I end up. However, in the present invention, since the sensor f6tJA itself is the measurement principle, there is no error introduced due to melting damage. Moreover, the sensor is specifically in the form of a coaxial cable, and has a simple structure and low cost.

〔Example〕

FIG. 1 shows an embodiment of the present invention, in which 50 is a container such as a ladle, 52 is molten steel in the container, and 54 is a slag layer on the surface of the molten steel. 10 is a sensor that detects the interface between molten steel and slag, 2
0 is its measurement part. Specifically, the sensor 10 is in the form of a coaxial cable, the center conductor is nickel chromium, the outer conductor is Inconel, and the dielectric between the inner and outer conductors is magnesium oxide. The sensor 10 and the measuring section 2o are connected by a coaxial cable 18 (for normal signal transmission), and this coaxial cable is supported and fed by a cable hanger. The sensor 10 is fed into the container 50 by a feeding device 42, and the feeding amount is controlled by a measuring roll 38, a pulse generator 40. It is determined by the sensor insertion length calculation section 26. 36
is a proximity sensor that produces an output when the tip of the cable sensor 10 passes through the sensor 36. 34 is a reference level detection section that generates a reference level signal in response to the output of the proximity sensor 36, 22 is a cable length calculation section, 28 is a molten steel level calculation section, 30 is a slag layer thickness calculation section, 32 is a display, and 44
is a laser distance needle that detects the slag layer surface position.

The length of the cable sensor 10 is measured by the TDR method.

To explain this with reference to FIG. 2, it consists of a measurement section 20, a pulse generator 12, an off-scilloscope 14, etc., and a rectangular wave pulse outputted by the pulse generator is transmitted through a coaxial cable 18. A composite wave of the incident pulse and the reflected pulse from the tip of the cable sensor 10 is observed with an oncilloscope 14. The observed waveform is as shown in curve C in FIG.

The reason for this is as follows. That is, sensor 10
If the load impedance Zt at the tip of sensor 1o is infinite (open), the reflected pulse from the tip of sensor 1o will have positive polarity as shown by the solid line in Figure 2 (C), and if 21 is 0 (short circuit), it will have positive polarity as shown by the dotted line. It has negative polarity.

This means that if the characteristic impedance of the sensor 10 is ZO, the reflection coefficient ρ is ρ= <Zt −Z o) / <Zt+
Z o), and if Zt=oo then ρ=1.21=0
Then, it is because ρ=-1. Therefore, the composite pulse is 2
If 1 is ■, solid line, 7. If t is 0, it will look like a dotted line. Second
Part C2 of curve C in figure (b) is a solid line rising waveform when Zt = ■, and a dotted line falling waveform when Zt =
When it is 0. The portion C1 of the curve C is due to the fact that the characteristic impedance of the sensor 10 is smaller than that of the cable 18.

The delay time t of the reflected pulse with respect to the incident pulse depends on the sensor length. That is, since this time t is the reciprocating distance 2L divided by the pulse speed C/h, the sensor length is L=
It is at C-t/2. Here, C is the speed of light and ε is the dielectric constant. This time t, as shown in Figure 2 (in bl, from origin O to CI
The sensor length can be calculated from the origin 0 to C2. The sensor length calculating section 22 in FIG.
Find the length of.

The sensor 10 is inserted into the container 10 by the delivery device 42, and the proximity sensor 36 produces an output when the sensor tip passes in front of it. The position of the proximity sensor 36 is known, and this position is set to the reference level L as shown in FIG.
o. Before inserting the sensor into the container 50, measure the sensor length to obtain a length of 10 (.The sensor 10 of length do is inserted into the container 50 beyond the reference level Lo while measuring the sensor length. As the sensor 10 enters the slag layer, the tip of the sensor eventually enters the slag layer, then enters the molten steel, and the part that enters the molten steel becomes red hot, but the sensor 10 becomes red hot when it enters the slag layer, but it does not melt (melt). Otherwise, if it enters the container steel, it will be eroded and damaged. Erosion damage can be seen by the shortening of the sensor length during repeated measurements.Furthermore, the cable sensor insertion length Δto from the reference level Lo is output by the detection unit 34. This can be determined by counting the output pulses of the pulse generator 40 from the time when the sensor insertion length calculation unit 26 generates the sensor insertion length.
fa tN length ΔlI is found as lo II, i1
The 4th level L1 is found as Δl1a−Δ11. The molten steel level calculating section 28 performs this calculation.

The distance meter 44 irradiates the laser beam, receives the reflected light, and detects the position of the reflective surface, in this example, the surface of the slag layer, from the receiving position. Once the slag layer surface position is determined, the slag layer thickness can be determined as the slag layer surface position minus the molten steel surface. The slag layer thickness calculating section 30 performs this calculation. The obtained slag layer thickness and/or molten steel level are displayed on the display 32.

FIG. 4 is a diagram showing the configuration of the sensor length measuring section, and parts corresponding to those in FIGS. 1 and 2 are denoted by the same reference numerals. 19 is a sampling unit, and 21 is an XY mark reading device. To read the X and Y coordinates, read the coordinates of part C2 of the waveform shown in Figure 2 (bl) displayed on the oncilloscope.
Perform waveform correction, etc.

If the sensor is melted by molten metal, it can be coaxial.
The shape is not limited to a bull shape, but a parallel conductor type cable shape or the like may be used.

〔Effect of the invention〕

As explained above, in the present invention, the molten steel level is known from the melting state of the sensor, etc., so there is no problem such as clogging of the conventional method, and reliable measurement can be performed. Further, the sensor structure is simple, inexpensive, and has the advantage of being easily affected by adverse environments such as high temperatures and dust.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing an embodiment of the present invention, and FIG. 2 is a T
FIG. 3 is an explanatory diagram of the DR method, FIG. 3 is an explanatory diagram of the measurement procedure, and FIG. 4 is an explanatory diagram of the cable length measuring section. In the drawing, 10 is a sensor, 50 is a container, 52 is a molten metal,
54 is a slag, 36 is a proximity sensor, and 28 is a molten steel level calculating section.

Claims (1)

[Claims] A molten metal level measuring method for detecting the interface level between the slag and molten metal in a container covered with slag, comprising: inserting a sensor into the container; and inserting a sensor into the container; The position is detected by a proximity sensor, the sensor insertion length Δl_0 is measured from the time of detection, and the length l_0 of the sensor before insertion into the container and the length l of the sensor after insertion are measured by the TDR method.
_1, find the sensor erosion length Δl_1 as the difference between these lengths l_0 and l_1, and calculate the molten metal level L
_1 is the position of the proximity sensor as L_0, and L_1=L
A method for measuring the level of molten metal, characterized in that it is determined as _0+Δl_0−Δl_1.