Innovative monitoring for glass production furnace

Edited by the Engineeringtalk editorial team Jul 4, 2001

An innovative monitoring system for the electrodes in glass production furnaces has been developed by F.I.C (UK), based on Eurotherm's versatile Visual Supervisor control system

An innovative monitoring system for the electrodes in glass production furnaces has been developed by F.I.C (UK) Limited of Penzance.

The company' s newly launched Electrode Maintenance Unit (EMU) continuously monitors and displays electrode performance, allowing wear or breakage to be picked up early enough to avoid refractory erosion or damage.

The heart of the unit is based on Eurotherm's versatile Visual Supervisor control system, providing a high level of operator information, with touch-screen display.

The EMU allows glass production personnel to fully monitor and determine the state of wear of the electrodes at any time during the furnace campaign.

Taking advantage of flash memory, it keeps a continuous record of electrode voltage and current, and is fully alarmed to alert operators of any problems detected with the electrodes.

System versatility is such that electrode holder temperatures are monitored as well as furnace voltage and current parameters.

Both control and display functions within the EMU are provided by Visual Supervisor, a multi-function process controller, data logger, setpoint programmer and interactive touch screen display combined in one unit.

The touch screen technology allows rapid user access to each monitoring mode and user-friendly display software ensures both ease of use and clear system graphics.

Visual Supervisor is capable of performing both continuous and sequential control, it features comprehensive alarm and event management, powerful trending, setpoint programming and local data logging facilities.

Measurement of both electrode and furnace parameters is handled through an adjacent Eurotherm 2500 System, which provides high performance, high accuracy I/O routing from furnace thermocouples as well as electrode current and voltage transducers.

This unit incorporates a number of unique hardware and software interactions that provide fast, accurate response times for analogue process control systems of the EMU type.

Undetected electrode wear or electrode breakage will lead to serious refractory erosion and possible glass leaks, thus shortening furnace life if not attended to promptly.

Most electro-heat specialists offer breakage and wear detectors with varying degrees of reliability but are generally unable to accurately determine the precise wear of multi-electrode poles.

This is because multiple electrodes connected to the same side of the transformer winding all detect the same signal.

Simple measurements such as determining the change in resistance are also unsatisfactory because electrode wear is not always uniform across the same circuit.

Thus, precisely determining individual electrode wear on each side of the transformer winding has until now been for all practical purposes impossible.

Similarly, probes used to measure relative voltage across the system can only average out the effect of wear on the multi-electrode poles.

This uncertainty can lead to over insertion of the electrode and the increased probability of breakage or, due to under insertion, increased current density close to the side- wall and hence accelerated wear of the refractory.

The F.I.C EMU overcomes these problems, as specially derived algorithms ensure that all multi-electrode poles are balanced prior to a general overall push, which resets the electrodes to their datum levels.

The software allows for breakage detection, balancing, and wear calculation, thus ensuring total electrode supervision and maintenance.