Three-phase material distribution measurements in a vertical flow using gamma-densitometry tomography and electrical-impedance tomography

Experiments are presented in which electrical-impedance tomography (EIT) an d gamma-densitometry tomography (GDT) measurements are combined to simultan eously measure the solid, liquid, and gas radial distributions in a vertica l three-phase flow. The experimental testbed is a 19.05-cm diameter bubble column in which gas is injected at the bottom and exits out the top while t he liquid and solid phases recirculate. The gas phase is air and the liquid phase is deionized water with added electrolytes. For the solid phase four different particle classes are investigated: 40-100 mum and 120-200 mum gl ass particles (2.41 g/cm(3)), and 170-260 mum and 200-700 mum polystyrene p articles (1.04 g/cm(3)). Superficial gas velocities of 3-30 cm/s and solid volume fractions up to 0.30 are examined. For all experimental conditions i nvestigated, the gas distribution shows only a weak dependence on both part icle size and density. The average gas volume fraction as a function of sup erficial gas velocity can be described to within +/-0.04 by a single curve. For most cases, the solid particles appear to be uniformly dispersed in th e liquid. (C) 2001 Elsevier Science Ltd. All rights reserved.