INTERACCIÓN ENTRE LA DINÁMICA DEL FLUJO DEL ACERO EN UN DISTRIBUIDOR DE 6 LÍNEAS Y LA TERMODINÁMICA DE SUPERFICIES EN EL SISTEMA METAL-ESCORIA-INCLUSIÓN

Abstract

Flow in a six-strand billet tundish, using turbulence inhibitors (TIs), was characterized using inputs of a pulsed tracer and mathematical simulations. It was found that to control turbulence attaining high fluid fractions under plug flow patterns, the key parameter for designing TIs is the dissipation rate of kinetic energy. TI designs that induce steep dissipation gradients are less efficient as flow controllers than those designs that yield more prolonged dissipation gradients from the inhibitor bottom to the bulk flow. A direct relationship between the dissipation of kinetic energy and the linear acceleration of the smallest turbulent eddies in the flow was established through dimensional analysis. The inhibitor with the highest linear accelerations of eddies in the viscous sublayer at the Kolmogorov scale, for a given liquid flow rate, yields the better flow control. As well as, the separation of non-metallic inclusions from the steel to the slag phase in the tundish is very important to the production of clean steel. Has been carried out a theoretical study of the separation of solid inclusions (alumina), at the steel–slag interface with the conditions of operation of the tundish. The theoretical model is based on the equation of motion with the following forces acting on an inclusion as it tries to cross the interface between the metal and the slag; buoyant, added mass, rebound and drag force. A parametric study was carried out in order to clarify which of the parameters in the model that had the largest influence on the inclusion displacement. The results showed that the interfacial tensions (σIM, σIS, σMS) have the largest influence on the displacement. It was also concluded that the overall wettability should be positive to obtain the most favorable conditions for inclusion transfer at the steel–slag interface. Finally, a dimensional analysis the main variables that take place in a tundish was carried out and where the Numbers Froude and Reynolds were obtained; in addition, a monomial equation that provides the ratio of the penetration nozzle with the height of turbulence inhibiter as a function of the nozzle Reynolds number and the Froude numbers of the nozzle and inhibitor itself.