Control of steel oxidation in reheating operations carried out with alternative fuels and new combustion technologies (CONSTOX) : final report

The aim of the project is to individuate the operating conditions to exploit innovative re-heating technologies (alternative fuels and new burners) maintaining or improving the quality of the products ensuring efficient descaling. Representative industrial scenarios were selected for defining reference conditions to be used in laboratory and pilot plant oxidation experimentation. The tests were performed with different mixtures, simulating gas from combustion of Natural Gas and other alternative fuels like Coke Oven Gas, Blast Furnace Gas and mixtures, using different heating conditions, temperatures and oxidation times. The use of non-conventional combustion gas does not change the basic aspects of the oxidation like the scale growth rate and the kinetic parameters. The tests allow to identify relations between oxidation conditions and scale morphology, defining a scale classification, and identifying criteria and tools for adjusting descaling conditions increasing surface quality in industrial operations. In particular the scale formed in atmosphere with lower water content favours descaling, but decarburization effects were observed using Blast Furnace Gas and Coke Oven Gas. A cost/benefits evaluation of the application of non-standard combustion technology was performed taking into account the environmental and cost benefits and effect on steel quality and guidelines for industrial application were individuated. The most appropriate operation mode can be realized by mixing Natural Gas with other fuels, which is advantageous when the access to the alternative fuel is easily given.