Influence of gas distribution and regime transitions on liquid velocity and turbulence in a 3-D bubble column

Laser Doppler anemometry has been applied to a bubble column equipped succe ssively with three different gas distributors: a single-orifice nozzle, a m ultiple-orifice sparger and a porous plate. Axial and tangential mean and r ms liquid velocity values have been measured up to a gas hold-up of 15-20%. A simple analytical model based on a bubble-induced turbulence is shown to be consistent with the results obtained with the three spargers and is use d to estimate the Reynolds shear stress. The evolution of the local hydrody namic parameters of the liquid phase with U-G is explained and related to t he hydrodynamic regime, the uniformity of the gas distribution and the star t-up procedure. (C) 2001 Elsevier Science Ltd. All rights reserved.