Measurements of solid concentration in a downward vertical gas–solid flow

Abstract

Abstract New results from experiments performed in a 15‐cm‐diameter downflow fast‐fluidized bed are presented. Tests were conducted at room temperature and near atmospheric pressure, with 125‐μm glass beads. Superficial gas velocities range from 0 to 6.6 m/s. Two different measurement techniques—gamma‐absorption tomography and capacitance sensing—were applied to the gas–solids flow in the downer tube. The average local solid fractions from both measurement techniques are compared for various operating conditions of the gas–solid flow. In general, good agreement was obtained between the solid concentration measurements from both measurement techniques. It is demonstrated that combined use of both measurement techniques offers the best chance to get time‐average information about the concentration distribution over the whole cross section.