Simulation On Temperature And Gas Flow Field In Hydrogen Direct Reduction Shaft Furnace

According to the our country present situation of iron and steel industry,now it is very necessary to find a ironmaking technology of high production efficiency,less environmental pollution,good product quality to take the place of the technology of high energy consumption,high environmental pollution,low product quality.Besides those advantages mentioned above,the gas-based direct reduction ironmaking technology is also short process and the products have lower impurity content,thus it has gradually become a hot topic of research at home and abroad.Against this background this paper is based on direct reduction process gas main equipment – shaft furnace temperature field and gas flow field.From the two aspects of the gas utilization ratio and reaching a predetermined temperature,the minimum gas demand of the shaft furnace was calculated.And the heat balance of the pellet was also computed.The pellet ventilation resistance was simulated based on DEM-CFD coupling and the fitting equation was used to calculate the pellet ventilation resistance.A gas-solid heat transfer model was built simulated with the FlUENT software.The pellets were as porous media and movement of pellets used sliding mesh method.Reduction reactions involved in the calculation using the three-step reaction,we can get the temperature field,reduced product changes with the height and thermal efficiency in the reduction zone of hydrogen direct reduction iron(DRI)shaft furnace.The results showed that with the increase of the throughput,the temperature gradient of reduction zone gradually narrows down,the temperature of the reduction gas at the outlet was higher and the thermal efficiency of the reduction gas was less.It indicated that the simplified gas-solid heat transfer model can be used to analyze the temperature field and reactants in the reduction zone of hydrogen DRI shaft furnace.Influence of bed conditions on gas flow in the DRI shaft furnace are simulated by DEM-CFD modeling.As to assess the gas flow under different bed conditions which are including shapes of the bed,different particle diameters,different gas velocity and particlemotion speed,a three-dimensional model has been built.The behavior of gas flow was investigated by a hybrid model of DEM-CFD coupling.The results show that the bed void differences which is caused by the packing way and particle diameter has an important influence on the gas flow and the shaped bed of ‘V' is the better choice to provide the optimal gas flow in the packed bed.The increase of blast velocity has great influence on the gas velocity distribution.When the descend velocity is 1 or 2 m h-1,it has little impact on the gas flow in the packed bed,and we can think that the bed is static.