ABSTRACT

Any model of fluidized-bed equipment requires information regarding its dynamics. As the present model does not include the momentum equations, such information should be given through empirical or semiempirical correlations. They would provide methods or equations to describe the following:

Dynamics related to the bubble phase. This item includes the rate of growth • of the bubbles in the bed, their pattern, their shape, the velocity of their ascent, maximum or critical size, etc. Another important question is, What is the fraction of the gas injected through the distributor that goes to the bubble

14.1 Introduction ............................................................................................... 315 14.2 Splitting of Gas Injected into a Bed .......................................................... 316

14.2.1 Quantitative Description ..............................................................317 14.2.2 Void Fractions .............................................................................. 318 14.2.3 Volumes and Areas ...................................................................... 320

14.2.3.1 Volume Ratios ............................................................. 320 14.2.3.2 Bubble Area-Volume Ratio ......................................... 320 14.2.3.3 Area Ratios .................................................................. 320

14.3 Bubble Characteristics and Behavior ........................................................ 321 14.4 Circulation of Particles .............................................................................. 323

14.4.1 Background .................................................................................. 324 14.4.2 A Review of Soo’s Work .............................................................. 326

14.5 Entrainment and Elutriation ...................................................................... 331 14.5.1 TDH ............................................................................................. 333

14.6 Particle Size Distribution .......................................................................... 333 14.7 Recycling of Particles................................................................................ 335 14.8 Segregation ................................................................................................ 337 14.9 Areas and Volumes at Freeboard .............................................................. 338

14.10 Mass and Volume Fractions of Solids ....................................................... 338 14.11 Further Study ............................................................................................ 339 14.12 Exercises ................................................................................................... 339

14.12.1 Problem 14.1 .............................................................................. 339 14.12.2 Problem 14.2 .............................................................................. 339 14.12.3 Problem 14.3 .............................................................................. 339 14.12.4 Problem 14.3 ..............................................................................340

References ..............................................................................................................340