Blast Furnace Refractory Wear Trend Monitoring
Blast furnace refractory lining is designed to survive very harsh conditions throughout the furnace campaign life. Nevertheless, refractory lining wear happens at various rates at different sections of the furnace for a wide variety of reasons. The main wear occurs at the hot face of the lining. Still, chemical attacks, particularly in the hearth and at the sidewalls, can be the main contributors to rapid loss of refractory that eventually results in the need for lining repair or replacement.
The most common method for monitoring refractory wear is by one-dimensional thermal calculation. This is done by collecting readings from a thermocouples network and converting the readings to refractory thicknesses using simple calculations. A more sophisticated method using thermocouple data analysis involves two- and three-dimensional finite element analysis (FEA), which provides a more reliable thickness profile of the lining. In addition to temperature-based calculations, acousto-ultrasonic measurements can also be used to determine the lining conditions. Both thermal and acousto-ultrasonic techniques have limitations that may produce false-positive or false-negative results. The main reason for false interpretation is the presence of chemical attacks within the lining that causes misinterpretation of the data. However, when thermal and acousto-ultrasonic data are combined, the presence of inner refractory chemical changes can be identified, and correct lining conditions can be determined. This paper demonstrates how important it is to combine the two refractory monitoring techniques to achieve accurate refractory lining thickness and condition results.