Particle velocity distributions were measured for a flow of 75-mu m FC
C particles in a CFB using a new video-digital camera technique. From
the spread of particle histograms, a random oscillating particle veloc
ity was determined This random velocity was used to compute the powder
viscosity with the help of dense-phase kinetic theory of granular flo
w. There was excellent agreement between this kinetic-theory measureme
nt and previous macroscopic viscosity measurements. The dimensionless
group kinematic viscosity divided by the oscillating velocity and part
icle diameter correlated all available data as a function of particle
volume fraction.