Investigation of Pobeda Furnace Bubbling Zone Physics Using Cold Modeling Method. Part 2. Hydro-Gas Dynamics of Liquid Blowing by Gas Using Bottom Gas-Protected Lance

Abstract

Cold flow simulation of Pobeda furnace bubbled bath hydro-gas dynamics was performed using a bottom gas-protected lance. It was shown that gas infusion into liquid at Archimedes criterion Ar = 5–60 is carried out in the pulse-coupled regime. The area of gas and liquid interaction was investigated at Ar = idem for separated and united air egress through ring and round nozzles. At all considered values of Ar, a two-phase zone was formed in liquid that was composed of “leg” with different geometrical shape, cavity, and gas-liquid layer over the bath surface. Characteristic features of blowing zone formation, flame configuration, and its structure in relation to the blow injection configuration and Ar values were found. It was detected that, at intense blowing through the lance center and ring gap, an ejected liquid prevailed in the cavity structure, the content of which increased upon increase in gas consumption in shell, but near the nozzle face, the “leg” is composed of the gas phase. A hypothesis was formulated that the presence of an additional amount of sulfide melt in oxidative streamline provides more complete magnetite destruction in the bath volume and at close proximity of the nozzle provides formation of a protective coating. The sizes of the most indicative geometrical areas of flame were quantified, which gave evidence about periodic and extreme behavior of jet spread in liquid. Empirical equations of the relation between maximum linear and across “leg” sizes at dynamical conditions of blow injection in shell (Ar_shell) and central tube (Ar_c) are obtained for two values Ar_shell ≥ Ar_cand Ar_shell ≤ Ar_c. It was estimated that blow injection in shell increases extension velocity of the “leg” on the nozzle face to 137 mm/s. The dependence of average height (H_avg, m) of splash lift over calm bath surface was defined, which at 25 ≥ Ar_shell ≥ 5 and 60 ≥ Ar_c ≥ 12 has the form H_avg = 0.027(Ar_shell + Ar_c)^0.27. Using Schlichting’s equation, a value of maximum offset from the nozzle surface where cooperative axial movement in liquid of ring and round flow with isovelocity is preserved is calculated. It is proposed that a protective effect of bottom lance with shell appears in the lance belt area over a distance of 7–10 cm from the nozzle surface. The cavity after separation from the nozzle moves down vertically, but countercurrent liquid flow bounding on the cavity front moves in the opposite direction, flowing around the phase interface with comparable velocity. On the basis of more intense change in the transverse size of the interaction zone in the nozzle area and noticeable sideways liquid movement, it was recommended to take corrective action for decreasing the action of melt erosion in the lance belt of the Pobeda furnace on the entrance region of flow development.