Minimization of Exergy Losses in the COREX Process

The COREX process is being projected as an alternative for blast furnace iron making. The coal consumption of the COREX process is large with a net fuel rate of ~1000 kg/tone of hot metal (THM). The reason for a higher net fuel rate of the COREX process compared with the net coal rate for the blast furnace process has been investigated. Exergy analysis has been performed for identifying the causes, locations, and magnitudes of process inefficiencies for the COREX process. Whereas blast furnace process data are available in the literature, no systematic data for stream information of the COREX process are available for different input coal rates required for exergy computation. A composite model of the COREX process (i.e., models for the smelter gasifier and the reduction shaft) using FactSage 6.2 (Thermfact/CRCT, Montreal, Canada, and GTT Technologies, Aachen, Germany) is used to generate stream data. A new methodology for the calculation of exergy of the COREX process streams using the database in FactSage is proposed in this work. Exergy data for blast furnace process streams have been obtained from the literature. The exergy loss and exergy efficiencies of the COREX process are evaluated at various coal rates and compared with those of the blast furnace. Operating the COREX process is theoretically feasible at lower coal rates with higher exergy efficiencies when lesser export gas is generated.