Bubble Characteristics Through Annular Permeable Refractory And Optimization Of Flow Field In Continuous Casting Tundish

Argon blowing is an effective method to remove small inclusions in molten steel of casting Tundish.The removal of inclusions in liquid steel by micro-bubbles plays an important role in the argon blowing metallurgical technology.As a permeable refractory for argon blowing,it seriously affects the formation and movement of bubbles.Considering the phenomenon of triangular blind area existing in the argon gas curtain,based on the actual conditions of permeable refractory in continuous casting tundish,The Euler-Eulerian muti-phase flow model was used to study the effect of the annular permeable refractory and gas flow rate on the molten steel flow field and the argon bubbles distribution in the continuous casting tundish.Alumina porous refractory was studied by the method of grain stacking.An annular permeable refractory of high strength for argon injecting the tundish was manufactured.The models of gas injecting through through-holes,slit type and porous permeable refractories were built.The bubble formation and movement through different permeable refractories into the liquid were studied using water model and numerical simulation.The following conclusions were obtained:(1)Annular porous permeable refractory was prepared using small grain of alumina,with a narrow particle size distribution and kyanite.High strength,little liner changing ratio,superiority gas permeability and uniform pore distribution were obtained in the sample.Micro-bubbles formed in the water model when gas was injected through the sample.(2)The simulation results showed that the formation and movement of bubbles were affected not only by blowing parameters,relative gas-liquid velocity,and wetting angle,but also by pore type,pore size,pore distance,and gas permeability of the permeable refractory.Porous permeable refractory with superiority gas permeability was easy to form micro-bubbles.Small bubbles with diameter rang 0.2to 2 mm formed through the through-hole material with small size pore,and moderate pore distance.Small bubbles formed when the gas flow rate was small and slit hole width was less than 0.15 mm,but no continuous gas curtain formed.(3)Annular bubble curtain formed around the stopper when argon was injected into the tundish through the annular permeable refractory installed in the tundish nozzle cup.All of the steel liquid entering the tundish nozzle were argon-washed,and part of argon flowed into the tundish nozzle,which had good effect on forbidding the tundish nozzle clogging.The width of the annular permeable refractory,distance from the center of the nozzle,and blowing parameters affect the molten steel flow field and bubble distribution.