Investigation of Pobeda furnace bubbling zone physics using cold modeling method Part 2. Hydro-gas dynamics of liquid blowing with gas using bottom gas-protected lance

Abstract

The cold flow simulation of the Pobeda furnace bubbled bath hydro-gas dynamics was performed using the bottom lance in a protective gas shell. It was shown that gas infusion into liquid at Ar = 5÷60 is carried out in pulse-coupled mode. The gas-liquid interaction area was investigated at Ar = idem for separate and joint air egress through ring and round nozzles. A two-phase zone was formed in liquid that consisted of a «leg» featuring different geometrical shape, a cavity and a gas-liquid layer over the bath surface at all considered Ar values. The most peculiar features of blowing zone formation, flame configuration and its structure depending on blow injection configuration and Ar values were found out. It was detected that ejected liquid prevails in the cavity structure at intensive blowing through the lance center and ring gap, and its content increases as gas flow rate rises in the shell, and the «leg» near the nozzle exit consists of the gas phase. An assumption was made that the presence of additional sulfide melt amount in the oxidative jet provides more complete magnetite destruction in the bath volume and protective skull formation in close proximity to the nozzle. Sizes of most indicative geometrical areas of flame were quantified, and they demonstrated periodical and extreme jet spread behavior in liquid. Empirical equations were obtained that describe the relation between maximum longitudinal and transverse «leg» sizes at dynamical conditions of blow injection into the shell (Ar shell ) and central tube (Ar center ) for two value ranges Ar shell ≥ Ar center and Ar shell ≤ Ar center . It was found that blow injection into the shell increases «leg» extension velocity on the nozzle exit up to 137 mm/s. The dependence of average splash lift height (H avg , m) above the calm bath surface was defined, which is H avg = 0.027(Ar shell + Ar center ) 0.27 within 25 ≥ Ar shell ≥ 5 and 60 ≥ Ar center ≥ 12 ranges. Schlichting equation was used to calculate the value of maximum offset from the nozzle surface where the joint axial movement of ring and round jets in liquid is maintained with equal velocities. It is assumed that the protective effect of the bottom lance with the shell appears in the lance belt area over a distance of 7–10 cm from the nozzle exit. It was noted that the cavity after separation from the nozzle moves down vertically, and the countercurrent liquid flow bounding on the cavity front moves in an opposite direction slipping the phase interface with comparable velocity. Due to more intensive changes in the interaction zone transverse size in the nozzle area and noticeable lateral liquid movement it was recommended to take corrective actions to decrease the erosive effect of melt in the Pobeda furnace lance belt at the initial jet development area.