Formation of fast fluidization and the vertical profile of solid concentration (2nd report, diffusive feature of fast fluidization)

摘要

It is necessary to predict the vertical profile of the solid concentration in designing essential features of fast fluidization reactors. The concentration of particles in the practical fast fluidization reactors decreases non-linearly from the bottom to the top. This paper proposes a diffusion equation for the vertical solid concentration profile, taking the following two points into consideration; the infinitely long chain has a large terminal velocity and each particle can take any velocity in a certain range. The diffusivity is then estimated from the movement of the growing chain based on the concept of "fractal", which is found to agree well with the experiments.