Numerical Simulation Of Liquid Steel Flow Field In 120 TLF Refining Process

In order to meet the increasing demand of steel quality,off-furnace refining technology has become one of the necessary links in steelmaking production.As a mature process,argon blowing at ladle bottom has been widely used in off-furnace refining.Its purpose is to stir liquid steel by blowing argon at the bottom to achieve uniform composition and temperature,remove gas and inclusions,etc.In this thesis,the LF furnace refining process will contact the liquid steel electrode through the refining slag,through the three-phase alternating current,under the action of electromagnetic force to promote the stirring of liquid steel,combined with bottom blowing argon to strengthen the flow of liquid steel,reduce the proportion of dead zone,shorten the refining time.Taking 120 t ladle of a plant as the research object,Ansys CFX simulation software was used to conduct numerical simulation research,and analyze the influence of different layout schemes,argon blowing amount and whether there is electromagnetic force on the flow characteristics of liquid steel,the stirring intensity of liquid steel,the volume distribution of argon in ladle and the proportion of dead zone.First,under the condition of traditional argon blowing at the bottom of ladle(without electromagnetic force),the position of blowing hole is changed,and the influence of blowing hole position on the stirring effect of molten steel in ladle is analyzed.The flow characteristics of molten steel,flow velocity of molten steel,volume distribution of argon gas in ladle and proportion of dead zone are discussed.By comparing the proportion of dead zone in different schemes under the condition of the same amount of argon blowing,it can be observed that the proportion of dead zone first increases and then decreases as the location of the blowing hole is further away from the central position.Under the same scheme,the proportion of dead zone in the ladle decreases obviously with the increase of the amount of argon blowing.Under the simulated conditions in this thesis,the arrangement scheme of blowing holes is 2/3R from the center of two blowing holes(Scheme 3),and the stirring effect of liquid steel is the best when the amount of blowing argon is set to 100NL/min.Secondly,the flow field morphology of liquid steel after applying electromagnetic force is simulated and analyzed,and the effect of changing the position of blowing hole and the amount of argon blowing at the bottom of ladle on the comprehensive stirring of liquid steel under the action of electromagnetic force is studied.Under the condition of the same amount of argon blowing,the proportion of dead zone from near to far from the center of the blowing hole decreases first and then increases.In the same arrangement scheme,the proportion of dead zone increases with the increase of the amount of argon blowing at the same time.Under the action of electromagnetic force,the blowing hole position is 1/2R away from the center(scheme 2),and the dead zone ratio of ladle is the smallest when the amount of argon blowing is 60NL/min.This scheme has the best comprehensive stirring effect of liquid steel in ladle.Finally,by comparing the numerical simulation results of no electromagnetic force and applied electromagnetic force when argon is blown from the bottom of ladle,the application of electromagnetic force can significantly improve the stirring effect of liquid steel in ladle under the same blowing volume.In addition,the amount of argon blowing in can be reduced by applying the electromagnetic force.The simulation results provide a feasible operation technology for LF furnace to shorten refining time.