Tunnel Pickling Flow Analysis

In the development of the continuous descaling process by pulling the rolled band through acid tanks, the band velocity was steadily increased by process technology innovations. Tunnel pickling is state of the art in this development process and allows band velocities up to 6 metres per second. The main challenges are to achieve a complete wetting of the band inside of the tank, a homogeneous supply with fresh and hot acid as well as a high flow turbulence in order to accelerate the pickling process and a contact free bearing of the band on the sliding stones at the tank bottom in order to avoid scrapes. In this contribution these effects are analysed and proposals for design optimisations are presented.