A Kinetics Model Of Decarburization In RH

With the fast development of modern science and technology,the requirement of steel quality is increasingly high for the national economy.As a result,the RH vacuum refining technique,of which the main function is to remove carbon from liquid steel,has been applied widely and developed rapidly.The removal of carbon is still taken as a half black-box process and therefore,the clarification of the process becomes the focus of many metallurgical researchers.It has to be noted that the above task can be accomplished by establishing a kinetic model for RH decarburization.Starting from the mass and energy conservation equations,a kinetic model for RH decarburization process is firstly developed in the present thesis and the main model parameters are chosen from the ones reported in literature according to a set of process data.The model is later on applied to investigate the effect of initial oxygen content,initial carbon content and vacuum pressure on RH decarburization process.The results show that decarburization is obviously prompted as the initial oxygen content is kept in a specific range,i.e.,below 500 ppm.Also,it is indicated that the final carbon content decreases with a decrease in either the initial carbon content or the vacuum pressure.In particular,as the vacuum pressure reaches 120 Pa,the removal of carbon is apparently better than the cases in other operational conditions.Considering the effect of recirculation flow rate and mass transfer coefficient in the process of RH refining,similarity law based physical modeling is also conducted in order to investigate the mechanisms of variations in the above two indexes and to further optimize the kinetic model built.In the experiments,both(regular)circular snorkel and irregular ones including oval and multi-branch snorkels are employed.The effect of snorkel type and gas flow rate on recirculation flow rate and mass transfer coefficient is assessed and the experimental results show that the two indexes are effectively enhanced by utilizing the irregular snorkels.In addition,it is indicated that with a specific snorkel type,both recirculation flow rate and mass transfer coefficient increase as the gas flow rate increases.However,the growth of mass transfer coefficient becomes slow as recirculation flow rate approaches a critical value.