CO2 Emission of CO2 Injection into Blast Furnace

As an energy-intensive industry, the iron and steel industry has been facing the challenges associated with reducing CO2 emissions. Therefore, metallurgical workers have been examining whether the steel industry can absorb some of the CO2 emissions. At high temperatures, CO2 is capable of oxidizing, which can lead to reactions with the carbon in the tuyeres raceway of the blast furnace to generate twice the volume of CO, improving the degree of indirect reduction and increasing the CO concentration in the top gas. In this study, metallurgical thermodynamics is used as the basis for constructing mathematical models of the mass and energy balance of a blast furnace and of the heat balance of a hot blast stove. Based on these models, the CO2 emission of CO2 injection into blast furnace is analyzed using the blast furnace CO2 emission model. Because of the endothermic reaction between CO2 and carbon, thermal compensation for the increases in the fuel ratio and oxygen enrichment is required. As the CO2 enrichment rate increases, the input of CO2 emission increases. However, as the CO concentration in the top gas increases and the top gas required by the hot blast stove decreases, the CO2 emission reduction at the output increases. When the CO2 enrichment limit is reached, the CO2 emission at the input increases by 530.97 kg/(tHM), the CO2 emission reduction at the output increases by 544.65 kg/(tHM), and the net CO2 emission decreases by 13.68 kg/(tHM). The high-quality top gas can replace a portion of the role of gas producers and reduce the CO2 emission of gas producers by 38.84 kg/(tHM). It can also prevent too much low-quality top gas from being released.