Research On Gas-liquid Two Phase Flow Behavior In RH Reactor

Mass transfer and heat transfer exist in RH vacuum cycle refining,and the chemical reactions and gas-liquid-solid multiphase flow also involved in the refining process.It is precisely relying on the gas phase blowing to drive the circulating flow of the molten steel in the RH refining device to achieve the refining effect of the molten steel,it can be seen that the flow behavior between gas and liquid phase is the main fluid motion behavior in RH refining.Therefore,studying the behavioral characteristics of the gas-liquid fluid in the RH refining process and exploring the relationship between the gas-liquid flow characteristics and the changes of various factors are essential to improve the refining effect and increase the RH refining efficiency.So,this subject uses two research methods,physical simulation and numerical simulation,to study the behavior characteristics of gas-liquid fluids in the RH refining process,so as to provide theoretical guidance for effectively improving the refining efficiency of RH equipment and perfecting the optimization of the refining process.This subject uses a 300-ton RH reactor in a steel plant as a prototype,and establishes a water model and a numerical model with a similarity ratio of 1:6 and1:1.Through the simulation experiments of the two methods,the effect of increasing the gas flow rate,the height of the vacuum chamber liquid level and the wall wetting characteristics on the gas-liquid fluid behavior in the RH refining process was explored;the gas-liquid two-phase flow pattern and the liquid level fluctuation behavior characteristics of the vacuum chamber are studied.All those research are on the purpose to provide theoretical support for improving the RH refining efficiency and increasing the steel-making speed.Research conclusion: The gas flow rate can effectively change the circulating flow rate of molten steel and the gas content rate in the riser.Larger gas volume speeds up the mixing process,and at the same time,the number of small bubbles will increase and the bubbles will tend to be irregular,and the flow pattern of the gas-liquid two-phase flow will change earlier,which will intensify the turbulence.With the liquid level in the vacuum chamber gradually rises,the liquid steel circulation flow reaches the maximum when the water mold is at a height of60?80mm,the gas content rate in the riser becomes smaller,and the bubbles gradually change from dense small bubbles to regular large bubbles.The number of bubbles at the same height is reduced,the flow pattern transition is lagging,and the turbulent state is improved.However,the increase of the gas flow rate and the liquid level of the vacuum chamber will aggravate the fluctuation of the liquid free surface.In the numerical simulation,when the wetting angle is from 0 to 180°,as the wetting angle increases,the velocity of the gas and liquid phases in the rise tube first decreases and then increases the rate,and finally tends to be saturated at about 150°.From the final conclusion,it can be seen that selecting an appropriate lifting gas flow rate and liquid level in the vacuum chamber,as well as a theoretical contact angle of 120°?150°,can promote the liquid phase flow,speed up the mixing process,and improve the refining efficiency.