Prediction of temperature in secondary steelmaking: mathematical modelling of fluid flow and heat transfer in gas purged ladle

Abstract

As a first step towards prediction of temperatures in secondary steelmaking, mathematical modelling of fluid flow and heat transfer in ladle furnace was undertaken. A two-dimensional quasi-single phase model has been developed for turbulent recirculating flow by solving Reynolds averaged Navier-Stokes equations along with a two-equation k-e model. The model was then extended to include thermal transport in a conjugate domain (i.e., molten steel + refractory shell + steel shell). The flow model was validated with water model data reported in literature by different researchers. Good agreement for velocity field and satisfactory agreement for turbulent kinetic energy field were obtained. The thermal model showed good agreement with results predicted in literature. The paper also presents findings of tests for sensitivity of flow on modelling and process parameters. By comparison with water model experiments, it has been demonstrated that the flow field in a ladle with a porous plug can be represented using a gas voidage fraction in the plume obtained from experiments with nozzles for axial gas injection from the bottom. Flow and thermal fields were insensitive to initial turbulence level at nozzle. Maximum temperature inhomogeneity in the melt was 2 °C after 1.5 min and negligible after 3 min of onset of gas purging.