Numerical Study Of Thermal And Flow Fields In A Galvanizing Zinc Pot

For several decades, the continuous hot-dip galvanizing process has been an important method of production of galvanized steel. Recently, the production of high quality zinc coated products has become an important demand by producers. The quality of coating is influenced by many factors. One of the well known factors is the dross, including the top dross (Fe2Al5) and bottom dross (Fe2Zn7 or FeZn13) which may stick to the surface of the strip and become spangles. Thus it is important to investigate the temperature distribution in the zinc pot, which largely affects the formation of dross. This paper tries to study the thermal and flow fields in a Galvanizing Zinc Pot by combining both numerical and experimental method. Moreover, the flow phenomenon of several working conditions are also involved in this paper.In this paper, to obtain accurate and properly imposed boundary conditions in the zinc pot, a two-step procedure for boundary condition treatment is presented for numerical study of the heat and flows in a continuous galvanizing zinc pot. In the two-step boundary condition treatment, the heat fluxes at the free surface, strip and the added zinc ingot, respectively, are firstly evaluated using the experimentally measured temperature signals and are calculated according to the heat balance. In the second, in order to obtain the heat fluxes and the Lorentz force imposed by the channel inductors, the coupled electromagnetic and thermal fields are numerically simulated in beforehand and then the results are added to the momentum and the energy equations, respectively, as additional sources posed by the electromagnetic field. With these treatments of boundary conditions, the heat and fluid flows in the galvanizing bath are numerically solved.In this paper, a numerical model of galvanizing zinc pot, including the calculation of coupled electromagnetic and flow fields, was built. The thermal and flow fields in different strip width, operation velocity and loading method of zinc ingot were calculated and analyzed, in order to investigate the influence of working condition on the zinc pot.