Study On The Kinetic Characteristics Of Vacuum Distillation In The Production Of Titanium Sponge By Magnesium Thermal Metho

Because of the excellent performance of titanium metal and titanium alloy,titanium has been widely used in aerospace,oceanographic industry,marine engineering,medical instruments,sports and leisure and other fields.However,the current distillation theory of titanium sponge production lags behind,and it is difficult to provide theoretical guidance in the current production process.In view of the slow rate of vacuum distillation process of magnesium thermal titanium sponge production,impurities are enriched in micropores and difficult to remove.In this paper,the thermodynamic conditions and influencing factors of microporous impurity volatilization during distillation are studied based on the augmented Young-Laplace Equation and Clausius-Clapyron Equation around the volatilization process of microporous impurities in vacuum distillation of magnesium thermal titanium sponge production.The coupling model of heat and mass transfer of volatile impurities in the micropores of titanium sponge was established through thermodynamic model,kinetic model and heat transfer model,aiming to complete the study of the kinetic characteristics of the distillation process of magnesium thermal titanium sponge production to improve the distillation efficiency,reduce energy consumption and improve the grade of titanium sponge.The main conclusions of this paper are as follows:（1）The factors that have an impact on the evaporation of the fluid in the micropores are analyzed,and through reasonable theoretical analysis,it is believed that the fluid fully wets the solid surface during the distillation process,and the influence of steam backflushing can be ignored.（2）The thermodynamic model was established,and the possibility of impurity removal was judged by the melting boiling point and saturated vapor pressure of volatile impurities.Based on the augmented Young-Laplace Equation and the Clausius-Clapyron Equation,the effects of fluid pressure distribution and interfacial temperature distribution on the distillation process in micropores were investigated.By deriving the augmented Young-Laplace Equation,a third-order differential equation controlling the thickness of the liquid film is obtained.The derivation of the Clausius-Clapyron Equation confirms that the interface temperature changes.（3）Based on the augmented Young-Laplace Equation,hydrodynamic model and heat transfer model,combined with the variable physical properties of working fluid at high ambient temperature,a coupling model of fluid heat mass transport in titanium sponge micropores was established.After simplifying the model using the fourth-order Runge-Kutta method,it is solved in Matlab ^TM.（4）The calculated value of the liquid film thickness of octane in the process of evaporative heat transfer was compared with the experimental value,and the results showed the same trend,and the calculation deviation of the model was confirmed to be within±15.00%,which confirmed the correctness and stability of the coupled model of heat and mass transport in this study.（5）Using titanium as the substrate and volatile impurities Mg and Mg Cl₂as working fluids,the effects of superheat,wall temperature and channel tilt angle on the distillation characteristics of molten fluid in titanium sponge micropores were investigated.It is found that changing the superheat is an effective method to improve the evaporation performance of volatile impurities in micropores compared with changing the wall temperature,and it is determined that the inclination angle of micropores has almost no effect on the evaporation performance.（6）The evaporation characteristics of volatile impurities during vacuum distillati on of magnesium thermal titanium sponge production were discovered.The dimensio nless relationship of evaporative heat transfer of volatile impurities during distillation was obtained,and the dimensionless relationship of Evaporative heat transfer between Mg and Mg Cl₂was Nu=154.43×Re^-2.96×10-4Pr^0.171and Nu=30.80×Re^-3.81×10-4Pr^0.075,re-spectively.