Cold Model On Air Dynamic Characteristics Of Swirling Premixed Metallurgical Burner

ABSTRACT:Particles dispersion and gas-particles mixing for a flash smelting furnace is the focus issue in smelting industry research. There are problems such as fluctuation of furnace conditions, raw concentration remain, shorten life of tower body and decreased oxygen usage about concentrated burners at high intensity of smelting process in flash smelting furnace. Designing a new burner is adapted to the need of high intensity flash smelting, exploring gas-particles mixing dynamic conditions near the nozzle exit, which provides the theoretical basis for the operation parameters control of new burner of flash smelting furnace.The gas-particle flow and mixing process in flash furnace is analyzed in this paper. Reynolds number, Stokes number and modified Froude number are selected to research the influence on gas-particle mixing and particles dispersion. Seven-hole probe is adopted to test three dimensional flow field inside the furnace, and high-speed photography technology capturing particles movement characteristics in the furnace, particles segregation distribution in the furnace and gray system are applied to get experimental correlations and the order of influence factors. The main conclusions are as follows.(1) The airflow is limited to a cylindrical zone around the center with20%of the reaction tower diameter, the outside of which exist air backflow. The gas-particle premixed zone is20%of reaction tower diameter and0.5times of the height. The axial and radial turbulent mixing of two-phase are strengthened by process air, and the tangent mixing of two-phase are enhanced by swirling air. Distribution air increases the radial velocity and reduces the tangential velocity, with obvious particles dispersion in furnace. The gas-particle premixed process enhances with increased swirling air velocity, or without distributed air.(2) High-speed camera is used to research particles trajectory. Process air makes particles focus on the center below burner, particles divergent angle decreases and tapered angle increases. Swirling air makes partilces disperse more evenly, particles divergent angle increases. Distributed air makes particles disperse along radial direction obviously, increasing particles divergent angle greatly, but larger distributed air makes particles jet along radial direction quickly, touching tower wall, causing corrosion and coking, affecting life of the reaction tower.(3) The methods of particles mass segregation is used to research particles dispersion. Particles mass segregation function increases with increased process air and decreased swirling air and distributed air, small size of particles is affected by airflow, and then change the inertia easily, feeding rate has little influence on particles mass segregation function.(4) Relevant formula of particles segregation function is exponential type, which is fited by Reynolds number and Stokes number from experimental datas. The formula refects the influences of Re&and Stk on particles segregation function, applied to121<Red<511,2.53<Stk<5.41, the local and prototype model are similar by calculation.(5) The sequence of factors affecting on mass segregation in furnace is process air velocity, particle size, swirling air velocity, feeding rate, and distributed air velocity.