Water modelling study of fluid flow and mixing characteristics in bath during AOD process

The fluid flow and mixing characteristics in the bath during the argon-oxyg en decarburisation (AOD) process have been investigated on a water model of an 18 t AOD vessel blown th rough two annu lar tube type lances of constan t cross-sectional area. The geometric similarity ratio between the model an d its prototype (including the lances) was 1 :3. Based on theoretical calcu lations of the parameters of the gas streams in the lances, the gas blowing rates used for the model were determined fairly precisely. Thus, sufficien tly full kinematic similarity between the model and its prototype was ensur ed. The influence of the gas flowrate and the angle included between the tw o lances was examined. The results demonstrated that the liquid in the bath underwent vigorous circulatory motion du ring blowing, and there was no ob vious dead zone in the bath, resulting in excellent mixing and a short mixi ng time. The gas flowrates, particularly that of the main lance, had a key influence on these characteristics. However, the gas jet of the sublance ha d a physical shielding effect on the gas jet of the main lance, and mixing efficiency could be improved by a suitable increase in the gas blowing rate of the sublance. The angular separation of the two lances also had a marke d influence on the flow and mixing in the bath. An excessively large or sma ll separation of the two lances would reduce the stability of blowing and w ould also be unfavourable to mixing. The optimum range of separation is 60- 100 degrees under the conditions of the present work. The relationships bet ween the mixing time and the gas blowing rate, the stirring energy, the mod ified Froude numbers for the main lance and sublance, the lance arrangement , etc. have been obtained. I&S/1413.