Exergy analyses of the oxygen blast furnace with top gas recycling process

The oxygen blast furnace with top gas recycling (TGR-OBF) process is an alternative ironmaking process, which brings tremendous potential to reducing energy consumption and CO2 emissions. An exergy flow model for the whole process is established and a computer application is programmed. The exergy analyses of the traditional blast furnace (TBF) and two kinds of TGR-OBF with different oxygen enrichment are carried out according to the computer calculation. On the basis of default operation parameters, carbon consumptions of two kinds of TGR-OBF processes decrease by 14.1% (case 1) and 20.2% (case 2) compared to that of the TBF process. The exergy indices in case 2 all improved, while these indices in case 1 all deteriorate except the first exergy consumption. In case 2, thermodynamic perfection degree and exergy efficiency increase by 1% and 4%, respectively. The exergy loss, the first and second exergy consumptions decrease by 47.7%, 16.2% and 5.0%, respectively. The first and second exergy consumptions increase with decreasing the exergy efficiency of VPSA (Vacuum Pressure Swing Adsorption). Thermodynamic perfection degree and exergy efficiency in both cases perform good linear relationship with the exergy efficiency of VPSA.