The Model Experiment on the Reaction between the Liquid and the Swarms of Gas Bubbles by NaOH-CO₂ System

Abstract

The gas bubble swarms has been applied as and effective means to the gas-melt reaction in many steel making processes such as the oxygen blow in electric furnace, or bottom blown oxygen converter operations. There have been, however, few fundamental studies available for understanding of the process because of the difficulty of estimation of gas bubble characteristic which is thought to be a basic factor for the reaction efficiency. Standing on this viewpoint, this study has been undertaken to clarify the influences of operation or vessel design at on this viewpoint, this study has been undertaken to clarify the influences of operation or vessel design conditions on the efficiency of gas-liquid reaction, mainly aiming at the bottom blown converter process, by applying the experimental technique of chemical engineering.
The model test of NaOH solution-CO₂ gas bubbles was conduted in the range of (Re) _n=10³-10⁴ and the effects of the gas blow rate, nozzle conditions, depth of liquid, directions of blowing etc. on the volumetric mass transfer coefficient A_KL were investigated by the continuous measurement of PH in solution. The results are summarized as follows:
(1) The diameter of nozzle, d₀ had little effect of A_KL, and A_KL was proportional to the gas blow rate V_m as expressed as A_KL=β. V_m 0.65 where β is a constant of proportionality.
(2) When the number of nozzle was increased, A_KL per one nozzle was decreased. This phenomenon may be explained by the cell model that the bulk is divided into the cells ruled by the number of nozzle.
(3) The effects of the liquid depth and end effect on A_KL were qualitatively illustrated for each bottom, side, top blowings.
Finally, the application of experimental technique of chemical engineering to the metallurgical research and the application of the present model teet to practical problems were discussed.