DENSE, VERTICAL GAS-SOLID FLOW IN A PIPE

The hydrodynamics of gas-solid flow, usually referred to as circulating fluidized-bed flow, was studied in a 7.5-cm clear acrylic riser with 75-mum 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.