Decarburization of Molten Fe-C Droplet: Numerical Simulation and Experimental Validation

Abstract

Decarburization of Fe-C droplet was investigated by fluid dynamics numerical simulation based on physical properties under gas phase mass transfer controlled regime. Fluid flow and species concentration fields around the droplet implementing a reaction of carbon with oxidant gas at the interface were calculated by a commercial CFD package which solves a set of transport equations. Overall decarburization rate of the molten Fe-C droplet was obtained by the simulation, and it was additionally validated by the present authors own experiment using gas-liquid drop reaction in a levitation melting equipment. It was observed by the simulation that decarburization rate on the surface of a droplet was not homogeneous due to inhomogeneous gas distribution around the droplet. A new concept of local mass transfer coefficient ratio was proposed in the present study as a ratio of effective local mass transfer coefficient at a specific site over average mass transfer coefficient, as a function of theta (angle between direction of gas flow and direction to reaction site on the droplet surface from the droplet center) and dimensionless numbers regarding fluid flow:

k(g)(local)/k(g)(average) = f(theta, Re-d, Sc)

Furthermore, effect of distance between two droplets was investigated by the present numerical model for decarburization of multiple droplets. The local mass transfer coefficient was found to have a significant impact on decarburization rate of a droplet when the other droplet locates very close. Relation between decarburization rate of two droplets and distance between them were analyzed.