A Water Model Experiment on Gas Absorption during Tapping

Abstract

Gas absorption phenomena during tapping from converter to ladle were studied by water model experiments. Gas absorption rate to molten steel was simulated by oxygen-water system and changes of dissolved oxygen in the vessels were continuously observed. In this study, effects of nozzle diameter and tapping height on volumetric coefficient for gas absorption rate, Ak_O, were investigated and gas absorption phenomena were discussed.

Changes of water amount in both upper and lower vessels were calculated with Torricelli’s law and changes of DO in lower vessel were estimated by the kinetics formula considering dilution. Maximum Ak_O was found in the early stage of tapping. Ak_O after the middle stage of tapping were in good agreement with reported values. Changes of Ak_O during tapping could be classified into 3 regions, I: Growth, II: Transition, III: Steady. The growth of plunge pool was also studied by estimating the depth of penetration of bubbles, H_p, during tapping and was associated to gas absorption phenomena. As a result, strong relationship between the gas absorption phenomena and the growth of plunge pool was confirmed. The similar behavior was found in various initial tapping height and nozzle diameter settings by estimating the experimental results with H_{p_obs.}/H_{p_calc.} and Ak_{O_obs.}/Ak_{O_calc.}. By using this similarity, experimental results could be reproduced by the empirical formula.