Ladle, Tundish, Vacuum Degas Refractory Preheat

Refractory vessels of various types are used in the melt shop or steel making area to hold molten iron or steel, known as hot metal.  Before hot metal is introduced to these vessels, the vessel must be preheated.  If hot metal is introduced to a cold vessel, then the metal can pop and explode over the sides of the vessel, creating a serious safety hazard.  If the vessel is heated to too low a temperature, then the refractory may be shocked and cracking and premature wear may occur.  If the vessel is preheated to too high a temperature, then energy is wasted, and the refractory may glass over, losing much of its effectiveness as an insulator.

Traditionally, the temperature status of these vessels has been monitored by inserting a thermocouple in the combustion gas exhaust stream.  It was thought that the rate of temperature rise of the refractory could be monitored by noting the temperature drop of the combustion gasses as they exit the vessel.  This crude approach to temperature control has proven to be inaccurate and costly.

The modern steel mill has replaced these troublesome thermocouples with low-maintenance infrared thermometers.  The infrared thermometer, providing a direct measure of refractory temperature, allows the refractory to be heated in a controlled manner and to a consistent temperature.  Better temperature control of the refractory results in significant fuel savings, shorter and more predictable soak times, and more consistent refractory temperature.  This more consistent soak temperature typically results in 20% longer refractory life, more consistent process temperature, and 17% lower fuel consumption.    In addition, the elimination of problematic thermocouple maintenance is perhaps an equally significant advantage of the infrared thermometer.

A fiber optic infrared thermometer usually is recommended for these applications in order to remove the sensor electronics from high ambient temperatures and heavy-abuse areas.  For preheat stations such as those with downward-facing (vertical) burners where the hot combustion gasses are likely to wash over the fiber cable, the ArmorGuard protective sheathing is recommended.