Simulation of the Effects of Hydrogen Injection on the Main Indicators of Blast Furnace and Carbon Dioxide Emission Reduction by Zero-Dimensional Model

Abstract

The steel industry accounts for about 7% of the total human carbon dioxide emissions, and faces enormous pressure to reduce emissions, especially the blast furnace (BF) process with high carbon dioxide emissions. BF hydrogen injection is one of the important technical measures for emission reduction. However, there are still few studies on the limit of hydrogen injection in BF and the influences of hydrogen injection on the changes of main indicators of BF. To evaluate the limits of BF hydrogen injection and these effects, this paper introduces in detail the application of Excel MMULT (MINVERSE (zone 1), (zone 2)) function to build BF mass and heat balance model and application of the Generalized Reduced Gradient (GRG) nonlinear optimizer of Excel Solver Add-In for BF operation optimization. The paper simulates the effects of hydrogen injection on the replacement of BF coke and pulverized coal, the reduction of CO₂ emission, the increase of production, and the changes of raceway adiabatic flame temperature (RAFT) and top gas temperature (TGT), the use of blast temperature (BT), and oxygen enrichment for thermal compensation. The possible limits of hydrogen injection are simulated. The influences on BF direct reduction degree (Dr), CO and H₂ utilization rate (ηCO and ηH₂) are also simulated. Further, the influences of hydrogen preheating injection on coke ratio, CO₂ emission reduction and use of BT, oxygen-enrichment for thermal compensation are simulated. The paper comprehensively and quantitatively evaluated the various aspects of BF hydrogen injection. The simulation results show that when hydrogen is injected at room temperature (298 K), under condition of full coke, 1250°C BT, oxygen enrichment and maintaining 1800°C RAFT, the maximum CO₂ emission reduction of the BF can reach ~30%. If the allowable RAFT is 1900°C, the maximum hydrogen injection volume is about 1/3 less than 1800°C, and the maximum CO₂ emission reduction will be ~20%. 1 kg/thm of hydrogen injected can replace about 2 kg/thm of carbon; this value varies with BT and oxygen enrichment rate, but is not affected by the composition of the mixed ore.