Water Model Study Of Bottom Blowing Stirring And Mass Transfer Between Slag And Steel In Converter

At present,the dephosphorization process is mainly controlled by the dynamic process of slag-steel interface.In the early stage of steelmaking,it is necessary to improve the dynamic conditions of the two phase interface to ensure the absorption of phosphorus as much as possible by slag.The suitable bottom blowing process can promote the stirring of the converter bath and the slag-steel interface,so as to improve the dephosphorization effect.Using 100t combined blowing converter model,the study carried on water simulation experiment.The experiment researched the top and bottom blowing influence on slag and steel interface stirring and emulsification in combined converter.It studied about the effect of bottom blowing intensity and the number of bottom blowing components on mixing process and mass transfer process under only bottom blowing.It also studied bottom blowing flow rate distribution,switching frequency on the mixing process,mass transfer process and emulsification process.Based on 100t converter model,the experimental results showed that:(1)On the condition of combined converter,the mixing time decreases with the increase of bottom blowing intensity.When the bottom blowing intensity is 0.3 Nm3/(t · min),the mixing time is shortened to 72.5%of the minimum bottom blowing intensity.When the bottom blowing intensity is less than 0.2Nm3/(t ·min),the mixing time decreases rapidly.The bottom blowing intensity is more than 0.20 Nm3/(t · min)and the mixing time decreases slowly.The bottom blowing intensity shouldn't be too large to waste gas and energy.(2)Combined blowing experiment showed that emulsion process is mainly affected by the impact of top blowing process.It produces a thick emulsion layer of oil and water.Only top blowing,the layer thickness increases with blowing time,and between the layer and water there exists a steady interface.The bottom blowing is main factor to break and stir the steady interface.With the bottom blowing intensity increasing,the layer becomes more and more fuzzy,the oil and water are fully mixed.Because the mass transfer process is affected by the emulsion layer,the mass transfer coefficient is unstable.(3)Because of the great effect of top blown on interface,the bath produces the thick emulsion.It's inadvisable to explore the influence of bottom blowing on bath stirring and interface stirring.So,experiments were conducted to investigate the effects of the number of bottom blowing components and bottom blowing intensity on the mixing time and mass transfer coefficient.Under the condition of only bottom blowing,there is no emulsion layer.The number of bottom blowing components and bottom blowing intensity determine the bottom blowing effect.The mixing time decreases with the increase of the bottom blowing intensity,while the number of bottom blowing components increases,the optimal value of mixing time appears later.The more of bottom blowing components,the greater increase of the mass transfer coefficient,and the later the optimal value appears.When the bottom blowing intensity of single bottom blowing component is 0.020-0.025Nm3/(t·min),the mass transfer coefficient can reach the best.(4)In continuous and spaced modes,with the bottom blowing distribution ration increasing,the mixing time decreases first and then increases;the mass transfer coefficient increases first and then decreases.Under the optimal distribution ratio of each process,the mixing time of continuous mode is shortened by 35.5%,and the mass transfer coefficient is increased by 80.5%;the mixing time of spaced mode is shortened by 35.5%;and the mass transfer coefficient is increased by 43.8%.On influence of distribution ratio mass transfer coefficient of continuous mode is greater than spaced mode;on mixing time is basically same.As the switching frequency increases,the mass transfer coefficient decreases with the increase of switching frequency.(5)Under the continuous mode,the mass transfer coefficient reaches the optimal value in distribution ratio of 4;mixing time in distribution ration of 5.Under the spaced mode,the mass transfer coefficient reaches the optimal value in distribution ratio of 3;mixing time in distribution ration of 4.The resistance of mass transfer process is greater than that of mixing process because the mass transfer process exists two phase interface resistance,which leads the optimal value of mass transfer coefficient appear earlier than that of mixing time.