The water modelling experiments of 300 t converter concerning combined blowing parameters, the number, and configuration of bottom nozzles are carried out. The results show that the arrangement of 16 bottom nozzles at...The water modelling experiments of 300 t converter concerning combined blowing parameters, the number, and configuration of bottom nozzles are carried out. The results show that the arrangement of 16 bottom nozzles at 0. 40D and 0. 45D （hearth diameter） concentric circles is the reasonable solution. The combined blowing steel- making technique of 300 t converter has been developed through experiments and studies relating to optimizing the top-bottom combined blowing pattern, the number and configuration of the bottom nozzles, the type selection of bot- tom nozzle, and bottom nozzle maintenance techniques. The results show that the product of w[c] ＂ w[o] at endpoint is reduced from 0. 002 62 to 0. 002 43, average TFe content is decreased by %, phosphorus distribution is raised from 70.85 to 78.95, sulfur distribution is raised from 3.43 to 4.32 and manganese content is raised by 0.02%.展开更多
The bubble growth and detachment behavior in the bottom blowing process were investigated. Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography ...The bubble growth and detachment behavior in the bottom blowing process were investigated. Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography and digital image processing. For these configurations, the experiments reveal that the bubble growth consists of a petal-like stage, an expansion stage and a detachment stage. The petal-like shape is qualitatively described through the captured images, while the non-spherical bubbles are analyzed by the aspect ratio. The bubble size at the detachment is quantified by the maximum caliper distance and the bubble equivalent diameter. Considering the dependence on the opening ratio, different prediction models for the ratio of maximum caliper distance to hydraulic diameter of the nozzle outlet and the dimensionless bubble diameter are established. The comparative analysis results show that the proposed prediction model can accurately predict the bubble detachment size under the condition of multi-hole nozzles.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 was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a...A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.展开更多
文摘The water modelling experiments of 300 t converter concerning combined blowing parameters, the number, and configuration of bottom nozzles are carried out. The results show that the arrangement of 16 bottom nozzles at 0. 40D and 0. 45D （hearth diameter） concentric circles is the reasonable solution. The combined blowing steel- making technique of 300 t converter has been developed through experiments and studies relating to optimizing the top-bottom combined blowing pattern, the number and configuration of the bottom nozzles, the type selection of bot- tom nozzle, and bottom nozzle maintenance techniques. The results show that the product of w[c] ＂ w[o] at endpoint is reduced from 0. 002 62 to 0. 002 43, average TFe content is decreased by %, phosphorus distribution is raised from 70.85 to 78.95, sulfur distribution is raised from 3.43 to 4.32 and manganese content is raised by 0.02%.
基金Project(51676211)supported by the National Natural Science Foundation of ChinaProject(2015zzts044)supported by Innovation Foundation for Postgraduate of Central South University,ChinaProject(2017SK2253)supported by the Key R&D Plan of Hunan Province,China
文摘The bubble growth and detachment behavior in the bottom blowing process were investigated. Four multi-hole nozzle configurations with different opening ratios were assessed experimentally using high-speed photography and digital image processing. For these configurations, the experiments reveal that the bubble growth consists of a petal-like stage, an expansion stage and a detachment stage. The petal-like shape is qualitatively described through the captured images, while the non-spherical bubbles are analyzed by the aspect ratio. The bubble size at the detachment is quantified by the maximum caliper distance and the bubble equivalent diameter. Considering the dependence on the opening ratio, different prediction models for the ratio of maximum caliper distance to hydraulic diameter of the nozzle outlet and the dimensionless bubble diameter are established. The comparative analysis results show that the proposed prediction model can accurately predict the bubble detachment size under the condition of multi-hole nozzles.
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financially supported by the National Natural Science Foundation of China(No.51704062)the Fundamental Research Funds for the Central Universities,China(No.N2025019)。
文摘A three-dimensional mathematical model was developed to investigate the effect of gas blowing nozzle angles on multiphase flow,circulation flow rate,and mixing time during Ruhrstahl-Heraeus(RH) refining process.Also,a water model with a geometric scale of 1:4 from an industrial RH furnace of 260 t was built up,and measurements were carried out to validate the mathematical model.The results show that,with a conventional gas blowing nozzle and the total gas flow rate of 40 L·min^(-1),the mixing time predicted by the mathematical model agrees well with the measured values.The deviations between the model predictions and the measured values are in the range of about 1.3%–7.3% at the selected three monitoring locations,where the mixing time was defined as the required time when the dimensionless concentration is within 3% deviation from the bath averaged value.In addition,the circulation flow rate was 9 kg·s^(-1).When the gas blowing nozzle was horizontally rotated by either 30° or 45°,the circulation flow rate was found to be increased by about 15% compared to a conventional nozzle,due to the rotational flow formed in the up-snorkel.Furthermore,the mixing time at the monitoring point 1,2,and 3 was shortened by around 21.3%,28.2%,and 12.3%,respectively.With the nozzle angle of 30° and 45°,the averaged residence time of 128 bubbles in liquid was increased by around 33.3%.
