Combustion of waste-derived fuels in Aluminum smelting plants

Abstract

Todays industrialized nations produce a steadily rising amount of waste containing huge amounts of valuable plastics and metals (i.e. WEEE, SLF) as well as waste resulting from refinery processes (i.e. PFO). These modern waste streams demand for alternative treatment methods to either expand their usage with recycling or to recover their energy, when recycling is not possible or economically feasible. Especially, intense metallurgic industries are highly dependent on fossil fuels and could benefit with respect to both CO2 emissions and fuel costs when a co-combustion together with waste-derived fuels would be applied. However, high shares of chlorine, sulfur and other problematic substances present in these modern waste streams can led to environmental and technical difficulties. Before experimental studies need to be done, combustion simulations can help selecting a potential fuel for co-combustion. In this work, seven different waste-derived fuels with differing yearly availabilities, compositions and heating values were investigated, regarding a potential co-combustion with propane in an aluminum recycling process. For the investigation, CHEMKIN PRO simulations were performed for each waste-derived fuel to consider their quantitative effect on the combustion. The results of the simulations together with other evaluation criteria, i.e. several environmental constraints regarding emission limitations and economical boundaries, were used to find the most promising waste-derived fuel for a potential future co-combustion in an aluminum smelting plant. According to the results of this thesis, PFO seems to be the most promising waste-derived fuel to be used in a future co-combustion process.