Theoretical Analysis on the Degassing Process in Upper Leg of R-H Degassing Plant

Abstract

It may be considered that the degassing rate in R-H degassing plant is mainly determined the rateof each the following processes, i. e., degassing process by inert gas bubbles in upper leg and one fromthe splash and the free surface of molten steel in vacuum chamber, and that these processes are affectedby circulation flow rate of molten steel.
To obtain the fundamental informations on the design of this plant and on the determination of theoperating conditions, a particular attention is devoted to the degassing process by inert gas bubbles inupper leg, and a mathematical model of this degassing process in two-phase flow including gas bubblesand molten steel is developed in this paper. And, this model consists of material and momentum balancein metal phase, material balance in bubble phase and equation of continuity for two-phase flow.
Numerical calculations on the degassing rate in upper leg and the circulation flow rate of moltensteel have been conducted with the aid of digital computer. Longitudinal distributions of process variablessuch as bubble size, pressure, concentrations of CO and H₂ in bubble phase and that of C, O and H in metal phase have been obtained over the range from the blowing point of inert gas tothe exit of upper leg under various blowing rates of inert gas. Calculated results on the circulationflow rate of molten steel were found reasonable by comparing them the comparison with previous datareported by other investigators.