A unified approach to bubbling-jetting phenomena in powder injection into iron and steel

The injection of powder into liquids has been investigated by physical modeling and by multi-phase fluid dynamic modeling. The transition from gas-particle jets which penetrate deeply into the liquid and a gas bubbling regime was found to depend on the coupling between gas and particle phases in the conveying line; fine particles at high loading couple well and form jets, whereas coarse particles separate from the gas during bubble formation. The measured penetration depths of submerged jets in water and lead and top jets in water were very well described by equations balancing the momentum of the jet and its buoyancy. A regime of particle-liquid jets that forms in conjunction with bubbling also appears to depend on coupling, between the particle and liquid phases. The effect of surface tension on the particle penetration through a bubble interface was modeled for the single particle and multi-phase cases and compared with the work of others. On the basis of this modeling, the expected regime of flow for many powder injection conditions can be predicted. The flow regimes of existing processes are discussed, and guidelines for the design of processes employing various types of reactions are presented.