Vibration Slag Detection System for Ladle (VSDL)

System for Early Slag Detection in the Process of Steel Pouring from Steel Ladle into Tundish
Vibration Slag Detection System for Ladle (VSDL)

Purpose

Vibration Slag Detection System for Ladle (VDSL) is designed for automatic detection of slag
penetration into liquid steel jet while pouring form Steel Ladle to Tundish. Upon detection of slag the
system generates sound alarm to the operator and/or signal to operate the slide gate of the ladle.


Functioning

  • Automatic system calibration in the process of steel pouring monitoring.
  • Detection of beginning of slag penetration into the stream of steel.
  • Setting of threshold for shutoff signal depending of slag content percentage in the steel tapping
  • channel.
  • Generation of sound alarm upon the formation of vertex or at penetration of slag into the steel
  • tapping channel.
  • Generation of Control Desk warning indication of exceeding the slag content threshold in the steel
  • tapping channel.
  • Generation of electric signal for closing of the Slide Gate (optional).
  • Automatic diagnostics of the system.
  • Recording and keeping of technological archives.
  • Providing uninterrupted power supply to the system.
  • Generation of messages regarding condition of the systems elements.
  • Data exchange with Automatic Process Control equipment.

Design and Principle of Operation

Schematically the system is show on Pic. 1.


1 - DSV Sensor; 2 PRM Panel; 3 - Cabinet.
Pic. 1 - VDSL Schematic Diagram
vdshs1.jpg


DSV Sensor measures the vibration of the pouring pipe, that gets conveyed to the Manipulator, along
the three orthogonal axises. At the time of vertex formation, or at time of slag penetration into the jet of
hot metal being poured, the vibration mode changes. This change of signal is identified by the system.
Calculated percentage of slag in the steel tapping hole is shown on the Caster Operators Panel
(PRM). When the set value is crossed, sound alarm is generated. PRM Panel is located nearby, at the work
place of the operating personnel. It has a display and operation buttons.
Cabinet is provided for processing of signals, generation of slag presence signal, system diagnostics,
recording of technological into operational archive as well as transmission of any information to the Shop
Process Control System. Cabinet contains PLC, PAC (Programmed Automation Controller), diagnostics
work station, Ethernet, uninterrupted power supply system and secondary power sources.

Sensor installation

Pic. 2 shows DSV Sensor installed on Casting Pipe manipulator.
 

Pic. 2 Photograph of Sensor in working condition

vdshs2.jpg

 

System implementation purpose is reduction in the amount of slag penetrating from Steel ladle into  Tundish. Main consequences of slag penetration from Steel Ladle into Tundish are as follows:
  • deterioration of steel purity due to presence of reduction products in the slag;
  • slag clogging of the tapping channel;
  • reduction of refractory life due to oxides induced erosion.
Economic effect of implementation of this system is manifold:
  • tundish life enhancement;
  • reduction of average residual steel amount in Steel Ladle and, thereby, increase of steel production;
  • improvement of steel quality.

Pic. 3 - Signal trends in VDSL system at the end of pouring

vdshs3.jpg


Pic. 3 shows typical signal trends of the system at the end of pouring. Few seconds prior to closing of the Slide Gate substantial change is seen in the signals from two measuring coils. Operator was closing the slide gate upon seeing the typical slag-like glow colour in the Tundish. As it is seen from the graph, the slide gate was closed 7 seconds earlier, as per the system generated signal.