Numerical Simulation Of "Spring" Phenomenon In A Melt Reduction Furnace

As one of the emerging non blast furnace ironmaking technologies,the HIsmelt smelting reduction ironmaking process is relatively mature,with advantages such as low raw material requirements,short process flow,simple operation,and low pollution gas emissions.Among them,the melt reduction furnace and material spray gun are important equipment for smelting and reduction in the process.However,in the actual production process,the furnace body is in a closed state,making it difficult to observe the internal spring phenomenon and the movement characteristics of each phase.Moreover,when the material spray gun is sprayed,the higher furnace temperature leads to a sharp increase in the temperature of the spray gun.If it is not cooled down in a timely manner,it will lead to a decrease in the lifespan of the spray gun and subsequently affect its performance,Directly affects the continuous and stable operation of the smelting reduction furnace ironmaking process.Therefore,in order to further study the HIsmelt ironmaking technology,observe the transient characteristics of each phase inside the closed furnace body,and optimize the structure of the material water-cooled spray gun,based on numerical simulation methods,this thesis uses a VOF multiphase flow model to establish a mathematical model for the molten pool area of the smelting reduction furnace.The effects of the position height,side blowing angle,and injection flow rate of the side blowing spray gun on the spray pattern and transient characteristics of the flow field in the furnace are studied;Finally,the structure of the spray gun was optimized by establishing water cooling models with different structures.The following conclusions are reached through research:The position of the spray gun has a significant impact on the spring phenomenon.When the height of the spray gun decreases,the nitrogen content in the slag liquid increases from 0.275m~3 to 0.403m~3,an increase of 46.5%.At this time,the stirring kinetic energy in the molten pool increases,which is more conducive to heat transfer in the upper and lower areas of the furnace.The injection angle will affect the airflow direction.The smaller the angle of the spray gun,the more severe the horizontal disturbance,and the influence range of the side gun gas will expand towards the furnace wall,accelerating the erosion of the furnace wall;And as the blowing angle increases,the maximum gas velocity in the longitudinal distance of the furnace decreases from18m/s to 9m/s,and the position where the peak appears gradually moves downwards with the increase of the angle.An increase in lateral blowing flow rate will increase the kinetic energy of the gas jet,and the disturbance of the slag layer will also increase,resulting in splashing at the gas-slag interface under the action of surface waves and shear forces.However,the maximum velocity of the transverse distance inside the furnace increases from 10m/s to 23m/s as the injection flow rate increases,leading to an increase in the annular flow inside the molten pool and exacerbating erosion of the furnace wall.The original design for the third and second cooling circuits has relatively high local flow velocities of 52.39 m/s and 33.37 m/s,respectively.These findings indicate that the initial structural design scheme may not be entirely optimal.Based on the original design,the improved design modifies the water flow path from the third circuit to the second and adjusts the direction of the water inlet and outlet.The simulation found that the maximum water flow velocity decreased to 10.63 m/s by changing the direction of the cooling water inlet and outlet,and the maximum water temperature in the loop was 58.73℃.This indicates that the new water cooling jacket design scheme is relatively reasonable and can meet the practical application requirements.In summary,the simulation results can provide reference suggestions for the selection and optimization of operating parameters for the HIsmelt melt reduction ironmaking process,and provide theoretical and computational basis for further development of new immersion melt reduction ironmaking technology in terms of process optimization and process control.