| RH vacuum refining equipment is one of the important refining methods in refining treatment outside the furnace.The realization of its refining function is closely related to the gas-liquid flow behavior inside the molten steel.The riser tube and vacuum chamber are the main reaction zones for the decarburization of the whole molten steel.In order to further improve the decarburization efficiency and refining efficiency of RH,it is necessary to conduct more in-depth research on the bubble characteristics,evolution law and liquid level fluctuation in the riser tube and vacuum chamber.In the actual production process,due to the limitation of high temperature,the relevant parameters cannot be accurately measured.Therefore,in this paper,a physical water model with a similarity ratio of 1 : 6 was established to analyze the bubble characteristics and bubble evolution law of riser tube and vacuum chamber under different gas flow rates and vacuum degrees.By collecting the liquid level fluctuation data of the vacuum chamber under different vacuum degrees and gas flow rates,the fluctuation form of the liquid level of the vacuum chamber and the erosion of the liquid on the wall are obtained.The main results are as follows :1.Study on bubble characteristics and evolution of riser and vacuum chamber :1)The initial diameter of argon bubbles in the riser tube decreased with decreasing vacuum degree.The diameter of argon bubbles in the riser tube increased with increasing gas flow rate.2)The main forms of bubbles in liquid are ellipsoidal shape,spherical cap and wobbling cap.In the process of rising motion,bubbles change from regular spherical to flat shape,and bubbles change from ellipsoidal shape to spherical cap.3)Bubbles in riser can be divided into stable single bubble rising zone and bubble coalescence broken zone.In the bubble rising region,the bubble velocity and bubble equivalent diameter are stable,and the overall stability of the bubble is high.In the bubble coalescence broken zone,the probability of collision and fragmentation between bubbles increases,and the turbulence intensifies.4)Variations in the gas flow rate and vacuum degree had significant effects on the regional distribution of bubble motion and bubble residence time.The critical height of the single bubble rising zone and the bubble breaking coalescence zone were stable when the bubble travel distance was greater than 280 mm.When the vacuum degree is reduced to the limit vacuum and RH treatment time is greater than 9 min,the bubble residence time tends to be stable.When the gas injection rate is constant,the reaction interface provided by the bubble tends to be stable.2.Study on volatility form of free liquid surface in vacuum chamber and mechanical erosion of refractory by Liquid Steel :1)The gas flow rate has little effect on the free surface fluctuation mode.The free surface fluctuation forms are similar under the same vacuum chamber height and different gas flow rates.The fluctuation amplitude increases with the increase of gas flow rate.2)With the increase of the liquid level height of the vacuum chamber,the erosion depth of the molten steel on the refractory gradually decreases under the same gas injection rate.When the liquid level height of the vacuum chamber is 80-100 mm,the single cycle erosion depth of RH is significantly reduced.Further increasing the liquid level height of the vacuum chamber increases the bubble distribution area inside the vacuum chamber,which is not conducive to improving the RH refining efficiency. |
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