Effects of top gas recycling on in-furnace status, productivity, and energy consumption of oxygen blast furnace

With its advantages of high productivity, high pulverized coal rate, low fuel rate, and low CO2 emissions, the oxygen blast furnace (OBF) process with top gas recycling is considered as a promising ironmaking process. In this work, a two-dimensional computational fluid dynamics model was established to simulate the transfer process and reaction behavior in an OBF with different flowrates of recycled gas. The effects of top gas recycling on in-furnace status, productivity, and energy consumption of the OBF were analyzed. The results indicated that, with an increase of the flowrate of the recycled gas in the shaft (under conditions ranging from 300 to 600 Nm3/t hot metal), the overall temperature, CO concentration, and degree of reduction in the OBF increased significantly. Comparing the performance of a traditional blast furnace with this system, the productivity of the OBF increased by 5.3%-35.3% and the energy savings reached 27.3%-35.9% when employing different criteria for energy consumption. This study may provide important perspectives for OBF application and industrial energy conservation.