Theoretical analysis on top gas recycling of gas-based shaft furnace

To adequatly utilize chemical potential of the reducing gas in gas-based shaft furnace, three processes with top gas recycling(TGR) are established and a process model based on the mass and energy balance is developed to numerically analyze the advantages and disadvantages of the proposed processes. The results show that in the proposed TGR1, TGR2 and TGR3 cases, the demand of the fresh hot reducing gas decreases by 63.77%, 57.13% and 55.85%, respectively, and meanwhile the requirement of the corresponding sensible heat shows the same tendency. However, the consumption of energy in each process increasess by 5.68%, 7.27% and 17.12%, respectively, because of the additional cost of the gas reforming and preheating. The emission of CO₂ for TGR1 decreases by 15.35% while the one for TGR2 and TGR3 increases by 0.16%, 3.15%, respectively.