Effect of the Density of a Microspherical Catalyst on the Operating Regimes of a Fluidized Bed

Abstract

An experimental study is performed of a circulating fluidized bed of two types of finely dispersed Geldart A particles with different bulk densities. The first type of particles have bulk density ρ_b = 1200 kg/m³, while the bulk density of the second type of particles is ρ_b = 1300 kg/m³. The studies are performed on a test bench 0.7 m in diameter and 5.75 m tall at room temperature with air used as the fluidizing gas. The velocity of fluidization ranges from 0.1 to 0.75 m/s. The bed is sectioned along its height with a set of horizontal diffuser grids. The results from measuring the fluctuations, the average drops in pressure, and the pressure distribution along the height of the fluidized bed are used to estimate the effect produced by the density of particles on its operational regimes. Velocity of transition U_c, determined from the mean-square deviations of pressure drop fluctuations, is 0.40 m/s for lighter particles and 0.35 m/s for heavier particles. Velocity of transition U_c determined from the power of the energy spectrum of pressure fluctuations Е is 0.45 and 0.40 m/s for lighter and heavier particles, respectively. The results from pressure measurements along the bed height show a linear drop with increasing bed height, and this drop is faster for heavier particles than for lighter particles.