Numerical Simulation And Influence Factor Analysis Of Multi-physical Field In Raceway Region Of Blast Furnace

Blast furnace is the key equipment in the ironmaking process.The pulverized coal combustion injected from the lower tuyere-raceway zone provides heat and reducing gas for the reduction of the iron ore,which further affects the shape and position of the cohesive zone and the distribution of gas flow.Therefore,raceway is very important for the stable operation of blast furnace.In this paper,a three-dimensional multi-physical field numerical simulation model of the blast furnace raceway is established,and the combustion process of pulverized coal and its influencing factors were analyzed and studied.The specific contributions and conclusions are as follows:（1）Based on the two fluid model,a three-dimensional numerical simulation model of blast furnace raceway formation process is established by using the numerical simulation method of coupling raceway formation and pulverized coal combustion process.（2）Based on the discrete phase model,a three-dimensional model of the coal injection combustion process in a blast furnace raceway was established,and the distribution characteristics of multi-physical fields in the raceway of a baseline case were simulated.The results show that the blasting speed decreases at the end of the raceway,and there is a high-temperature area.The generated CO₂ begins to transform to CO at the end of the raceway through boudouard reaction.Most of the pulverized coal is burned in the raceway,and the burnout rate in it is 57.39%.（3）The effects of key parameters（oxygen concentration and coal injection ratio）on pulverized coal combustion and multi-physical field distribution in the raceway were analyzed.The results show that as the oxygen concentration increases from 27%to 31%,the average bosh outlet temperature increases by 65 K,and the burnout rate increases from 73.58%to 78.55%.When the coal injection ratio increases from 125 kg/t to 155kg/t,the high-temperature zone mainly expands along the radial direction,and the overall burnout rate decreases from 77.64%to 70.10%.（4）A three-dimensional simulation model,including the cohesive zone,was established.Influence of the shape and position of the cohesive zone on the distribution of multi-physical fields in the blast furnace raceway was investigated.The results show that due to the poor gas permeability at the cohesive zone,the temperature at the bosh outlet is 1925K,which is 123 K lower than that without considering the cohesive zone,and the gas outlet velocity is also reduced from 1.47 m/s to 1.44 m/s;In addition,the low permeability of the cohesive zone also reduces the size of the raceway,resulting in the overall burnout rate reduced from 73.85%to73.04%,and the burnout rate of the raceway reduced from 57.39%to56.22%.Pictures 64,Tables 20,Reference 70...