LAG-S100 Ladle Slag Detection System (Eddy Current)

LAG-S100 Ladle Slag Detection System (Eddy Current)



Overview

The continuous casting ladle slag detection device is used to detect the
slag content of the ladle nozzle in the steelmaking continuous casting
process, so as to improve the cleanliness of the tundish molten steel and
obtain the best yield of the ladle molten steel. The device adopts the
principle of electromagnetic induction detection.





The meaning of slag detection

To achieve high output: In order to ensure the cleanliness of molten steel
in the ladle, if we detect slag by eyes, we often close the ladle
prematurely, so that it will reduce the yield of molten steel. However, if
we use slag detection system, we can detect slag accurately and timely, so
that the amount of residual steel is controlled at 1%-2% to achieve high
output.

Improve the cleanliness of molten steel: The steelmaking slag gets into the
tundish is the main reason that affects the cleanliness of finished steel.
The use of the slag detection system can reduce the amount of steelmaking
slag carried into the tundish to a very small amount, and can also reduce
the defects on the slab surface at least 80%.

Avoid blockage of the nozzle: The steelmaking slag gets into the tundish is
also the main reason for the blockage of the nozzle due to secondary
oxidation. After using the slag detection system, the blockage of the nozzle
can be greatly reduced.







The composition of the system

The slag detection system mainly consists of five parts: sensor,
preamplifier, signal processing unit, central processing unit and platform
control box.











System control flow chart







The working principle of the sensor

The sensor adopts the principle of electromagnetic induction for signal
detection, and its typical structure is two concentric coils. When the
primary coil is supplied with an intermediate frequency excitation current,
due to the action of the magnetic field, an eddy current is generated in the
steel flow, and the direction of the magnetic field is opposite to the
direction of the magnetic field generated by the coil. Because the
conductivity of slag is much lower than that of molten steel at high
temperature (about 1/1000), the eddy currents generated in slag are much
smaller than those generated in molten steel. In the process of pouring
steel, all the molten steel flows out at the beginning of pouring. At the
later stage of pouring, there will be steelmaking slag mixing out, which
reduces the conductivity of the melt and enhances the electromagnetic field.
This signal is measured by the secondary coil.






The principle of sensor construction

The primary coil and the secondary coil are isolated by high temperature
resistant materials, and the coils are encapsulated in a flat ring made of
special steel as a whole. Then two pairs of signal lines are drawn from the
two-pole coil using a unique technical method, and sent to the secondary
part.



The installation of the sensor

The sensor is installed in the ladle reference plate, coaxial with the ladle
nozzle, and acts as a guide part for the ladle nozzle casing tube at the
same time.





The technical Features
The ladle slag’s coil made of imported materials and installed at the
bottom of the ladle as a guide component for the ladle nozzle can work
normally in an environment of 900 °C for a long time, achieving no burning,
no damage and good weak slag signal detection characteristics . The average
service life of the sensor reaches more than 800 furnaces.

The signal connector of the ladle slag coil can meet the reliable connection
of the microvolt level (1uV=10-6V) slag signal under the conditions of high
temperature, high impedance and strong oxidation, and realize the repeated
use of long-term zero impedance.

After the ladle slag coil works for a long time in a high temperature
environment, changes in distributed parameter characteristics such as
impedance cause signal drift. The system can automatically identify and
compensate, which ensures the accuracy of system signal processing and
alarming.

The function is complete, which can actually reflect various information of
molten steel casting. It has various functions such as curve storage, status
display, alarm display, output control, and information printing, etc.,
which can effectively meet the requirements of the production process.



The technical indexes

Sampling time: <10ms

System response time: <0.1s

Zero point average volatility: <4%

System detection value accuracy: <5% (duty ratio)

Slag volume alarm setting value: user-defined (recommended to use 20%)

Average sensor life: >800 furnaces



The working condition

Sensor use ambient temperature: <900℃

Operating temperature of secondary instrument: <40℃

Storage and transportation temperature of secondary instrument: -20℃-+70℃

The relative temperature used by the secondary instrument: at 25°C, the
maximum is 95%

Minimum Order: 1 pieces

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