Determination of thickness and quality of refractory linings in industrial furnaces using acousto ultrasonic echo

Refractory linings in metallurgical furnaces undergo deterioration and wearing with time. The deterioration is caused mainly by thermomechanical mechanisms leading to cracks, chemical degradation and loss of heat transfer capability. Any sudden failure of the lining is dangerous and could affect the structural integrity of the furnace, leading to production loss and costly refurbishment. Non-destructive testing (NDT) and monitoring of refractory lining would lead to better safety, longer use of the vessel, production optimization, controlled maintenance and increased production. Thickness measurements and monitoring of the refractory lining in operating furnaces is possible using Acousto Ultrasonic -Echo (AU-E) technique. This technique uses stress waves of both acoustic and ultrasonic ranges in order to determine thickness and integrity. This thesis presents the details of AU-E technique in addition to laboratory measurements to determine parameters leading to the in-situ measurements. Finally, three case studies are presented to substantiate the theoretical and laboratory measurements.