• Energy Research

Top gas recycling oxygen blast furnace (TGR-OBF) process is a promising ironmaking process. The biggest challenge of the TGR-OBF in operation is the dramatic decrease of top gas volume (per ton hot metal), which once led to hanging-up and shutdowns in practice of the Toulachermet. In order to avoid this weakness, the strategy of medium oxygen blast furnace was presented. The maneuverable zone of the TGR-OBF was determined by the top gas volume, which should not be far from the data of the traditional blast furnace. The deviation of ±12.5% was used, and then the maneuverable blast oxygen content is from 0.30 to 0.47 according to the calculation. The flame temperature and the top gas volume have no much difference compared to those of the traditional blast furnace. The minimum carbon consumption of 357 kg per ton hot metal in the maneuverable zone occurs at the oxygen content of 0.30 (fuel saving of 14%). In the unsteady evolution, the N2 accumulation could approach nearly zero after the recycling reached 6 times. Thus far, some TGR-OBF industrial trials have been carried out in different countries, but the method of medium oxygen enriched TGR-OBF has not been implemented, because the accumulation of N2 was worried about. The presented strategy of medium oxygen enriched TGR-OBF is applicable and the strategy with good operational performance is strongly suggested as a forerunner of the full oxygen blast furnace.

Top gas recycling oxygen blast furnace (TGR-OBF) process is a promising ironmaking process. The biggest challenge of the TGR-OBF in operation is the dramatic decrease of top gas volume (per ton hot metal), which once led to hanging-up and shutdowns in practice of the Toulachermet. In order to avoid this weakness, the strategy of medium oxygen blast furnace was presented. The maneuverable zone of the TGR-OBF was determined by the top gas volume, which should not be far from the data of the traditional blast furnace. The deviation of ±12.5% was used, and then the maneuverable blast oxygen content is from 0.30 to 0.47 according to the calculation. The flame temperature and the top gas volume have no much difference compared to those of the traditional blast furnace. The minimum carbon consumption of 357 kg per ton hot metal in the maneuverable zone occurs at the oxygen content of 0.30 (fuel saving of 14%). In the unsteady evolution, the N2 accumulation could approach nearly zero after the recycling reached 6 times. Thus far, some TGR-OBF industrial trials have been carried out in different countries, but the method of medium oxygen enriched TGR-OBF has not been implemented, because the accumulation of N2 was worried about. The presented strategy of medium oxygen enriched TGR-OBF is applicable and the strategy with good operational performance is strongly suggested as a forerunner of the full oxygen blast furnace.

The Arrhenius temperature integral is typically used in non-isothermal kinetic analysis, which is widely applied in gas–solid reactions in separation processes. In previous studies, researchers provided various methods to solve the temperature integral, but the error usually became significant when the value of x (x = Ea/RT) was too large or too small. In this paper, we present a new series method and design a computer program to calculate the temperature integral. According to the precise calculation of the temperature integral, we first reveal the relationship among the integral, the temperature, and the activation energy, and we find an interesting phenomenon in which the 3-D image of the temperature integral is of self-similarity according to fractal theory. The work is useful for mechanism and theoretical studies of non-isothermal kinetics.

The Arrhenius temperature integral is typically used in non-isothermal kinetic analysis, which is widely applied in gas–solid reactions in separation processes. In previous studies, researchers provided various methods to solve the temperature integral, but the error usually became significant when the value of x (x = Ea/RT) was too large or too small. In this paper, we present a new series method and design a computer program to calculate the temperature integral. According to the precise calculation of the temperature integral, we first reveal the relationship among the integral, the temperature, and the activation energy, and we find an interesting phenomenon in which the 3-D image of the temperature integral is of self-similarity according to fractal theory. The work is useful for mechanism and theoretical studies of non-isothermal kinetics.

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.

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.