MODELING TURBULENT FLUIDIZED-BED REACTORS - TRACER AND FIBER OPTIC PROBE STUDIES

Phenomenological models for turbulent fluidized beds are presented in this study. These models are based on a ''core-annulus'' representatio n of the turbulent fluidized bed. Three how regions are considered: (1 ) gas flows through a dense annular region and is either perfectly mix ed or in plug Bow; (2) gas circulates in the core as bubbles in plug f low; (3) gas is perfectly mixed in a dense emulsion phase, also in the core zone. The models also account for mass transfer between differen t regions by assuming various possible gas exchange paths. A new techn ique which combines novel reflective fibre optic probes and statistica l signal treatment is used to measure local flow properties. Results f rom fibre optic experiments coupled with those from an inert non-adsor bing tracer (helium) allow for mass transfer parameter assessment. The se data demonstrate the importance of incorporating an annular region in the simulation of the main bed section of turbulent fluidized beds. Modelling results of this work strongly suggest the critical importan ce of gas exchange between bubbles in the core and a pseudohomogeneous annular region.