Tundish Level
The EMLI Tundish Level Measurement System
EMLI System Description:
The EMLI™ (Electro Magnetic Level Indication) system utilizes state-of-the-art technology in the measurement and detection of liquid metal levels. The basic EMLI system architecture consists of a MANAGEMENT UNIT, a CONTROL UNIT and a PREAMPLIFIER UNIT. In multiple system applications, one MANAGEMENT UNIT can monitor up to eight (8) CONTROL UNITS.
The MANAGEMENT UNIT is used to monitor the system, log data, and for set-up and troubleshooting. If enabled the system can be remotely evaluated through the MANAGEMENT UNIT via an Internet connection.
The CONTROL UNIT is the heart of the system. It generates the transmitter signal and receives and evaluates the measurement signal.
The PREAMPLIFIER UNIT increases the level of the measurement signal before it is fed to the CONTROL UNIT.
EMLI - Tundish Level Measurement System:
The EMLI Tundish level measurement system is a robust instrument that reliably and consistently measures the level of the liquid metal in a continuous caster tundish. The system provides a constant, real-time, level output for monitoring or automatic level control.
The system utilizes two sensors that are mounted between the metal tundish shell and the refractory lining. These sensors have been designed for long life and can easily last from one tundish relining to the next.
An IMPORTANT feature of the EMLI Tundish Level Measurement System is the ability to accurately measure the tundish metal level in the tundish from the bottom refractory to the overflow spout. This allows the user to achieve maximum metal yield while assuring that no slag enters the continuous caster mold.
As mentioned previously, the EMLI tundish level measurement system utilizes two sensors. One sensor is designated the transmitter and the other is designated the receiver. The sensors are usually placed opposite each other in the tundish vessel. The transmitter sensor is excited with a AC current. This causes the transmitter to emit an electromagnetic field. This field is direct coupled to the receiver sensor. When the metal level in the tundish is low, the electromagnetic field has a clear path to the receiver sensor and a strong received signal is detected. When the metal level in the tundish is high, a portion of the electromagnetic field is shielded from the receiver sensor and the received signal is reduced. This manner of level measurement produces an output signal that is directly proportional to the level of metal in the tundish.
It is important to note that the presence of slag on top of the metal has no affect on the EMLI measurement system. The system provides the actual metal level regardless of slag content in the tundish.
amount of eddy currents produced is diminished. This results in a smaller magnetic field and a weaker received signal.
System Benefits:
The fact that the EMLI Tundish Level Measurement System accurately measures the actual level of the metal in the tundish (as opposed to weight) allows the system to offer the modern steelmaker the following benefits:
- The ability to precisely drain the tundish at the end of a continuous casting sequence. This provides a measurable increase in yield while minimizing the size of the residual skull remaining in the tundish. Some customers have reported that the realized increase in yield paid for the cost of the system in eight (8) months or less.
- When the EMLI system tundish level system is utilized as the input to the automation tundish level regulation system the actual metal level in the tundish remains stable thus resulting in a constant ferro-static head pressure over the tundish taphole. The stable head pressure enables the mold level control system to work more efficiently and therefore there is a resultant improvement in the mold level control.
- Due to the ability of the EMLI system to give accurate and precise level information is it possible to minimize the steel intermix zone during ladle changes. This can result in significant savings due to less downgrading and additional processing.