Improvement of purging plugs performance by investigations on the materials, process analysis and continuous monitoring - Impurgingar : final report

The research programme was aimed at improving the purging plugs performance (desired gas injection flow rate through the plug for an adequate working time) in argon stirring operations. From the fundamental point of view, the thermochemical effect of the interaction between the plug refractory and the process has been investigated, in particular, concerning slag formation under the process temperature conditions, and the interaction between such a slag and steel. In parallel, the plugs thermo mechanical behaviour was studied, since thermal shock during stirring results in very strong mechanical stresses, harmful for the refractory. The technology of measuring refractory wear during working has been suitably applied to purging plugs. A thermal sensor has been improved and tested at laboratory scale. The proven technology, that foresaw thermocouples positioned along plug thickness, has been used for industrial trials to measure purging plug wear. Plug wear has been evaluated on the basis of the measured temperature and thermal distribution along the plug thickness. The solution adopted on plant in order to improve the purging plugs performance has foreseen the use of gas controller system, to detect the plug occlusion, and the implementation of gas maintenance procedure, aimed to remove the plug occlusions by blowing gas at high pressure. The technology capability was verified in detecting and solving the conditions of plug fully or partly 'blocked'.