Andreas Osterkorn, Mirko Javurek, Philipp Gittler, Andreas Mehrle,
"Numerical, Experimental and Analytical Investigation of the Mass Outflow from a Pickling Tank"
, in Kudriavtsev, V., Kleijn, C.R., Kawano, S.: ASME PVP, Serie 2004 ASME/JSME Pressure Vessels and Piping Conference (July 25-29,2004), San Diego, USA, Vol. 491-2, Seite(n) 191-199, 2004, ISBN: 0-7918-4686-5
Numerical, Experimental and Analytical Investigation of the Mass Outflow from a Pickling Tank
Sprache des Titels:
The process of pickling is an important intermediate step in the production line of steel processing. The strip surface is cleaned from grease and scales before further processing by immersion into an acid bath. Problems arising at higher process speeds with increasing inclination of the free surface are reduced strip immersion length and increased mass outflow.
In this paper a differential equation is derived describing the influence of the bath depth on the local surface inclination for a simplified two-dimensional case. Since it can only be solved analytically for trivial boundary conditions a numerical solution has been computed giving an estimation for the order of growth of the bath inclination and mass outflow with the strip velocity. Further, a series of CFD simulations of the complete three-dimensional geometry at different strip velocities have been carried out calibrating the formulas of mass outflow. In the course of the CFD simulations the deformation of the free surface was calculated by a VOF model with explicit reconstruction of the interface. A standard k-e turbulence model was applied and special considerations have been made regarding the boundary conditions. Finally the resulting formula has been verified making use of data from a small scale model.
It was found that the overflow at the far end of the tank is the dominant mass transfer mechanism at process velocities of the current generation of pickling tanks. Still, due to the superior order of growth, mass drag-out via the upper side of the strip becomes important for process velocities of 8 to 10 m/s. The good accordance of the analytical solution, CFD simulation and experiment indicate that the formula derived in the first part of the paper is a good estimation for the mass outflow from the pickling tank, hence making time and resource consuming CFD simulations obsolete for the design layout. Further the validity of geometrically non similar small scale models could be showed.
Sprache der Kurzfassung:
2004 ASME/JSME Pressure Vessels and Piping Conference (July 25-29,2004), San Diego, USA