| At the background of national“double carbon”,developing low-carbon iron smelting technology is the crucial method to reduce the consumption and emission of blast furnace（BF）ironmaking process.In the situation of that traditional BF ironmaking technologies are difficult to improve,enriched hydrogen injection can change the fuel structure of BF to achieve the goal of reducing the consumption and emission of BF ironmaking process.For stable operation of BF,the effects of hydrogen injection（HI）on operation and energy utilization of BF should be studied.According to the operation parameters and geometry of a 5050 m3 BF,modeling the tuyere-raceway zone and the flow characteristics and combustion mechanism in the raceway were studied.Exergy balance model of hydrogen exergy was established and energy efficiency utilization of enriched hydrogen blast furnace ironmaking process was analyzed.In order to explore the effect of HI on blasr furnace roundabout,a model of BF tuyere-receawy with HI is established,and the numerical simulation of BF with HI is carried out.The results show that when the he HI flow rate is 50 m3·t-1,the volume of raceway decreases by 8.81%.Besides,with the increase of 10 m3·t-1 HI flow rate,the adiabatic flame temperature decreases by 14℃,and the gas flow in the furnace increases by 46.91 m3.For keeping adiabatic flame temperature and gas flow in the furnace stable,heat compensation is needed,that is,for every increases of 10 m3·t-1 HI flow rate,bosh gas flow should be reduced by 71.53 m3,oxygen enrichment rate should be increased by 0.59%for every 10 m3·t-1 hydrogen injection.In order to clarify the change of pulverized coal combustion characteristics with hydrogen injection,the numerical simulation of hydrogen and pulverized coal combined injection is carried out.The results show that when the hydrogen injection flow rate is below 35 m3·t-1,hydrogen will promote the combustion of pulverized coal in the raceway zone and vice versa.The combustion rate and consumption rate of hydrogen are much higher than that of pulverized coal.Hydrogen has better combustion performance than pulverized coal.This shows that the combustion in the raceway zone can be improved by the proper flow rate of HI.In addition,when the hydrogen injection flow rate is 50 m3·t-1,increasing the coal ratio can reduce the burnout rate of pulverized coal,but the burnout ratio still increases.The coal ratio increases by 20 kg·t-1 and the combustion ratio increases by 5.34 kg·t-1.In order to clarify the effect of HI on blast furnace energy utilization,the exergy balance model of blast furnace exergy balance was established and calculated.The results show that as the concentration of reducing gas in top gas increase with HI flow increase,when the HI flow is 50 m3·t-1,the chemical exergy of top gas increase by470.66 MJ·t-1,compared without HI.In addition,exergy efficiency of blast furnace increased by 1.76%and thermodynamic perfection degree of BF increased by 3.90%.It means that HI is helpful to improve the energy utilization inside the BF,and the adverse effect of HI on the energy utilization of BF will be greatly reduced if the top gas can be properly utilized.The influence of HI on the process parameters of BF is summarized.The results show that when the HI flow is 50 m3·t-1,the temperature of top gas decreases by 36℃,the ratio of ore to coke increases by 9.21%,the total consumption of reducing agent decreases by 7.47%,the utilization rate of total reduced gas increases by 1.41%,and the carbon emission of BF decreases by 8.26%.Hydrogen rich operation has a certain impact on the process parameters of blast furnace.The results show that the maximum hydrogen injection flow rate is 120 m3·t-1when the adiabatic flame temperature and the top gas temperature drop is kept within50℃,and the maximum hydrogen injection flow rate can be increased by high temperature hydrogen injection.Besides,when the HI flow is 50 m3·t-1,the ratio of ore to coke increased by 9.21%,the total consumption of reducing agent decreased by7.47%,the utilization rate of total reducing gas increased by 1.41%,and the carbon emission of blast furnace decreased by 8.26%. |
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