A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationsh...A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.展开更多
In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid stee...In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.展开更多
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...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.展开更多
The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied ...The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.展开更多
基金financially supported by the State EconomicTrade Commission of China (No.OIBK-098-02-07)
文摘A nozzle clogging online forecasting model based on hydrodynamics engineering was developed, in which the actual flow rate was calculated from the mold width, thickness, and casting speed. There is a linear relationship between the theoretical flow rate and the slide gate opening ratio as the molten steel level, argon flow rate, and the top slag weight are kept constant, and the relationship can be obtained by regression of the data collected at the beginning of the first heat in each casting sequence when the nozzle clogging does not occur. Then, during the casting, the theoretical flow rate can be calculated at intervals of one second. Comparing the theoretical flow rate with the actual flow rate, the online nozzle clogging ratio can be obtained at intervals of one second. The computer model based on the conception of the nozzle clogging ratio can display the degree of the nozzle clogging intuitively.
基金the National Natural Science Foundation of China(Nos.51874215 and 51974213).
文摘In continuous casting,the argon blowing at the tundish upper nozzle is usually used to prevent nozzle clogging,whose effect is closely related to the migration of argon bubbles and the flow behavior of the liquid steel in the nozzle.Here,to investigate the effects of argon blowing at the tundish upper nozzle on multiphase flow behavior in nozzle,a threedimensional model of the tundish–nozzle–mold was established for numerical simulation.The results indicate that the argon bubbles injected from the inner wall of the tundish upper nozzle first move downward along the nozzle wall under the action of the liquid steel.As the distance from the tundish upper nozzle increases,the argon bubbles gradually diffuse to the center of the nozzle.Compared with no argon blowing,the liquid steel velocity increases in the center of the nozzle and decreases near the wall with argon blowing.With increasing the argon flow rate,the concentration of bubbles in the nozzle increases,and the process of bubble group diffusion to the center region of the nozzle speeds up.This in turn increases the liquid steel velocity at the center of the nozzle but reduces near the wall.With increasing the casting speed,the concentration of bubbles in the nozzle decreases,the length of the bubble group near the nozzle wall is extended,and the liquid steel velocity at the center region and near-wall region of the nozzle increases.The mechanism of argon blowing at the tundish upper nozzle to prevent nozzle clogging is mainly realized by the isolation effect of the argon bubble group on the inner wall of the nozzle.
基金funded by the National Natural Science Foundation of China(Nos.51874215 and 52204351)the China Postdoctoral Science Foundation(2022M722487).
文摘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.
基金the financial support of the Natural Science Foundation of Inner Mongolia Autonomous Region of China(No.2020MS0517)Science and Technology Project of Inner Mongolia Autonomous Region of China(No.2020GG0109).
文摘The type of inclusions in tundish steel and the formation mechanism of the submerged entry nozzle(SEN)clogging in the continuous casting of the rare earth(RE)high strength steel without calcium treatment were studied based on the plant trials and thermodynamic calculation.It was found that Ce_(2)O_(3) and CeAlO_(3) in tundish molten steel were transformed into Ce_(2)O_(2)S+CaO-Al_(2)O_(3) with the size of 2-3 lm during cooling.When the flow velocity of molten steel on surface of the SEN was slow due to the boundary layer effect,Ce_(2)O_(3) inclusion in molten steel reacted with Al_(2)O_(3) in the SEN refractory to form CeAlO3.With the continuous erosion of molten steel and reaction,the compositions of CeAlO_(3),Al_(2)O_(3) and CaO were aggregated,and the clogging layers with different zones were formed on surface of the SEN.Meanwhile,a small amount of molten steel remaining in the arc zone and corner zone of the SEN formed solidified steel.When calcium treatment is canceled,the reaction probability between inclusions in molten steel and refractory should be reduced by improving the material and shape of the SEN.
