Numerical study of effect of φ(CO)∶φ(H2)on reaction process in a direct reduction shaft furnace
With the development of hydrogen production technology,it is feasible to use green hydrogen as a reduc-ing agent in gas-based direct reduction shaft furnace.Among many non-blast furnace ironmaking technologies,the hydrogen-rich direct reduction shaft furnace process is expected to solve the problem of high CO2 emission in tradi-tional blast furnace long process.However,the common problem faced by the hydrogen-rich direct reduction shaft furnace is that when the volume percent of H2 is too high,the reduction heat absorption leads to insufficient heat in the furnace,which affects the gas utilization rate and metallization rate.How to adjust the φ(CO)∶φ(H2)of reduc-tion gas,make the CO reduction process release heat to make up for the heat absorbed by H2 reduction,and cooper-ate with other operating parameters and the optimization of furnace structure to fully utilize the physical energy and chemical energy,so as to improve the utilization rate of gas and metallization rate,has become an urgent problem to be solved for the hydrogen-rich direct reduction shaft furnace.In order to solve this problem,this paper established a two-dimensional CFD mathematical model of hydrogen-rich direct reduction shaft furnace,and investigated the in-fluence of φ(CO)∶φ(H2)in reduction gas on the multiphase and multi-field distribution of shaft furnace.The CFD model was validated by means of comparing simulation results with industrial test data.The results show that when the volume percent of H2 in the reduction gas increases,the temperature in the shaft furnace continues to decrease.With the increase of the volume percent of H2,the utilization coefficient of H2 decreases while the utilization coeffi-cient of CO increased slowly.The comprehensive utilization coefficient of reducing gas shows a trend of first increas-ing and then decreasing.When the volume percent of H2 is 60％,the comprehensive utilization coefficient reaches the highest of 0.28.The mole percent of Fe concentration at the outlet of the furnace shows a trend of first increas-ing and then decreasing with the increase of the volume percent of H2.When the volume percent of H2 is 40％-50％,the highest mole percent of Fe can reach 95.67％.In the actual practice,maintaining the φ(CO)∶φ(H2)in the reduced gas at around 40％:60％can achieve high gas utilization rate and product metallization rate.
hydrogen-enriched direct reduction shaft furnaceφ(CO)∶φ(H2)reaction processnumerical simula-tiongas utilization coefficient
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