Numerical simulation on gas–liquid multiphase flow behavior under coupling effects of annular gas curtain and swirling flow at tundish upper nozzle

A three-dimensional mathematical model has been established for a novel metallurgy process coupling an annular gas curtain with swirling flow at tundish upper nozzle. The discrete phase model and volume of fluid model were applied to simulate the gas–liquid multiphase flow behavior in tundish and nozzle. The effect of argon flow rate on the migration behavior of bubbles and interface behavior between steel and slag was also investigated. The presented results indicate that the novel coupling process can significantly change the flow pattern in the stream zone of a tundish, prolong the average residence time of liquid steel, and reduce the dead fraction. A complete annular gas curtain is formed around the stopper rod of tundish. Under the action of drag force of liquid steel, a part of small bubbles enter the nozzle through the swirling grooves and gather toward the center of the nozzle by centripetal force. As the argon flow rate increases, the volume fraction of argon gas entering the nozzle increases, which enhances the swirl intensity and increases the concentration of bubbles in the nozzle. To avoid the formation of slag open eye in tundish, the argon flow rate should not exceed 8 L min−1.

Process optimization of billet continuous caster and practice verification

This study analyzes the factors of influence on 0~# continuous caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation(hereinafter referred to as Basteel).Diameter of tundish upper nozzle is small,and the molten steel leakage accidents have been greatly manifolded in the high casting speed.In order to increase yield of 0~# continuouse caster in No.1 Steelmaking Plant of Xinjiang Bayi Iron & Steel Corporation,and a series of amelioration measure was put forward.Through enlarging diameter of tundish upper nozzle(fromφ21 mm toφ21.5 mm ),after the water distribution of the secondary cooling was optimized.Based on stabilizing the quality,improving the average casting speed and work rate of the caster,the capacity of the billet continuous caster was improved.A better results was gained;the average casting speed had been increased from 3.04 m/min to 3.21 m/min.Production of the caster had been improved from 1 005 179.926 t in 2008 to 1 040 853.075 t in 2009.Quality of the concasting billets and production had also been stabilized.