高炉低碳喷吹条件下回旋区质能平衡分析

Analysis on mass and energy balance of raceway at low-carbon injection conditions for blast furnace

风口喷吹参数的变化是氧气高炉、富氢气体喷吹等高炉低碳炼铁技术的共性特征。为了深入理解高炉低碳喷吹条件下回旋区的热量供给及炉腹煤气变化,基于Cantera软件构建并验证了考虑热风、喷吹气体、煤粉及焦炭的回旋区质能平衡模型,探究了喷吹气体量、喷吹气体成分、热风氧含量、风口鼓入总气量等参数对回旋区理论燃烧温度和炉腹煤气体积、成分的影响。以维持合理的理论燃烧温度和炉腹煤气量为标准,探究了各喷吹参数之间的调和平衡关系。研究表明,对于喷吹CO+H_(2)双组分气体工况,维持鼓入总气量1100 m^(3)/t和鼓入总氧量300 m^(3)/t可基本保证回旋区理论燃烧温度和炉腹煤气量在合理范围,最大可喷吹气体量随热风氧含量增加而增加。喷吹气体中H_(2)含量的增加,会促进回旋区HCN的生成而导致风口焦炭消耗量略有上升、理论燃烧温度略有降低。喷吹CO+H_(2)+CH43组分气体时,CH4含量的增大导致理论燃烧温度显著下降、炉腹煤气体积显著增大。喷吹富氧干馏煤气、焦炉煤气、纯甲烷3种甲烷含量不同的气体时,喷吹量每增大50 m^(3)/t,需将鼓入总气量分别减少22、30、85 m^(3)/t,鼓入气体总氧含量分别提高2.0%、2.5%、8.5%,以维持理论燃烧温度(2423±1)K、炉腹煤气量(1450±1)m^(3)/t。各种常温气体的喷吹均会造成风口消耗的焦炭量增多,但炉腹煤气还原势随喷吹气体体积增大而显著提高,有助于发展间接还原,从而实现碳减排。

Variation of tuyere injection parameters is a common feature of low-carbon blast furnace ironmaking technologies such as oxygen blast furnace and hydrogen rich gas injection.To deeply understand the change of raceway heat supply and bosh gas composition at low-carbon injection conditions,a raceway mass and energy balance model based on Cantera software is established,which considers the participation of the hot blast,co-injected gas,pulverized coal and coke.Effects of injection parameters including the co-injected gas flow rate and composition,hot blast flow rate and its oxygen concentration on the raceway theoretical combustion temperature and the volume and composition of bosh gas are explored.Based on the standard of maintaining reasonable theoretical combustion temperature and bosh gas volume,the conditional balance of injection parameters is explored.The results show that for CO+H_(2) two-components gas injection,maintaining the total gas flow rate of 1100 m^(3)/t and the total oxygen flow rate of 300 m^(3)/t can basically ensure reasonable raceway theoretical combustion temperature and bosh gas flow rate.The maximum co-injected gas volume increases with the increase in oxygen concentration of blast.Increase of H_(2) content in co-injected gas would promote the formation of HCN in the raceway,resulting to a slight increase in raceway coke consumption and decrease in the theoretical combustion temperature.When CO+H_(2)+CH4 three-components gas is injected,increase of CH4 content would lead to significant decrease in theoretical combustion temperature and increase in bosh gas volume.For injection of oxygen-rich pyrolysis gas,coke oven gas and pure methane,which have different methane concentrations,an increase of 50 m^(3)/t in the co-injected gas volume requires decrease in the total volume of blast and co-injected gas by 22,30 and 85 m^(3)/t,and increase in the total oxygen concentration by 2.0%,2.5%and 8.5%respectively,to maintain the theoretical combustion temperature of(2423±1)K and the bosh gas volume of(1450±1)m^(3)/t.Injection of cold gases would increase the coke consumption at the tuyere,but the reduction potential of bosh gas increases significantly,which can promote the indirect reduction and contribute to the decrease of carbon emission.