| With the development of national economy,the requirement of intelligent manufacturing and green production for iron and steel enterprises is increasingly urgent.Blast furnace burden structure optimization has became the mainstream development trend of iron-making industry.Pellets are one of the important components of burden structure.As the last stage equipment to control the output and quality of pellets,the cooling process of pellets in the annular cooler has been lack of systematic research and analysis due to the limitation of complex conditions such as high temperature and closed on-site.Therefore,it has became a vital research topic to simulate the cooling process of pellets by numerical simulation and to explore the changing law of the cooling process of pellets.Focusing on the production process of the annular cooler in a pellet factory in China,based on the heat exchange characteristics involved in the pellet cooling process,and on the basis of using Fluent,a numerical calculation model for the cooling process of pellets are established and selected,and the calculation area is divided by referring to the physical model of the actual structure 1:1 trolley.The turbulence model is selected as realizable model.Five working conditions are simulated for different porosity,different bed height,different particle size,different inlet gas velocity and different inlet gas temperature.The single working condition for pellets are studied and summarized one by one.The influence law of temperature field in cooling process and the influence law of outlet flue gas temperature on waste heat utilization were obtained,and the optimized process parameters were obtained.The main conclusions are as followed:1)The temperature of flue gas and pellet increases with the same cooling time,which is perpendicular to the upward direction of bed height.At the same bed height,the temperature is basically the same,and the heat exchange is basically the same.The flue gas velocity is smaller in the middle of the material layer and higher in the bellows and the upper part of the material layer.2)The error between simulation results and actual data is less than 10%.The model is believed to be reliable.3)The influence of single thermal parameter adjustment on the cooling process of pellets: At the same time,the pellets' temperature decreasing with the increase of porosity and inlet gas velocity,the pellets' temperature increasing with the increase of pellet size,inlet gas temperature and bed height.4)The influence of single thermal parameter adjustment on flue gas temperature and waste heat at outlet: In the range of 650mm-750 mm,increasing bed height,in the range of 393K-413 K,increasing inlet gas temperature,in the range of 0.4-0.6,decreasing bed porosity,and in the range of 6mm-18 mm,reducing pellet size,can increase outlet flue gas temperature and waste heat utilization.In the range of 1.6m/s-2.0m/s,increasing the inlet air velocity,the outlet flue gas temperature is decreased,but the waste heat utilization is increased.5)Obtained the optimum parameters of pellet cooling process: The porosity of material layer is 0.4,the velocity of inlet gas is 1.8m/s,the particle size of pellet is 12 mm,the inlet gas temperature is 400 K,and the height of bed height is 750 mm.Figure 34;Table 5;Reference 47... |
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