1987 Volume 13 Issue 5 Pages 671-677
Fundamental flow behavior of a solid particle in a CFM-bed, such as minimum fast fluidization velocity, particle holdup, particle velocity distribution, and residence time, were observed in a two-dimensional visualized cold model by use of three kinds of solid particle : alumina balls, activated alumina balls, and coal particles.
The minimum fast fluidization velocity, defined as the critical gas velocity to form a stable state of a fast fluidized bed or an entrained bed in the inner pipe, almost corresponded to the terminal velocity of a single particle. When a solid particle with a high apparent density was employed, however, a slight increase of the minimum fast fluidization velocity was recognized with an increase in the height of the inner pipe. Particle holdup and particle residence time showed similar trends to those of the glass beads in the previous study, exponentially decreasing with an increase in superficial gas velocity in the inner pipe. The velocity distribution of the solid particle was slightly affected in the inner pipe by the apparent density of the particle, but was nearly in the free falling flow region in the annular part.
