Dense, vertical gas‐solid flow in a pipe

Abstract The hydrodynamics of gas‐solid flow, usually referred to as circulating fluidizedbed flow, was studied in a 7.5‐cm clear acrylic riser with 75‐μm FCC catalyst particles. Data were obtained for three central sections as a function of gas and solids flow rates. Fluxes were measured by means of an extraction probe. Particle concentrations were measured with an X‐ray densitometer. In agreement with previous investigators, these data showed the flow to be in the core‐annular regime, with a dilute rising core and a dense descending annular region. However, unlike the previous studies conducted worldwide, the data obtained in this investigation allowed us to determine the viscosity of the suspension. The viscosity was a linear function of the volume fraction of solids. It extrapolates to the high bubbling‐bed viscosities.