Entrainment and Elutriation from Fluidized Beds

Correlation on the Particle Entrainment Rate in Gas Fluidized Beds

“…Four relationships on the decay constant of the axial solid holdup profile have been proposed by Kunii and Levenspiel, Adanez et al, Choi et al, and Lei and Horio . To investigate the best correlation, those relationships have been compared with the data in Table 3 in the report by Lei and Horio .…”

“…Their experimental conditions are summarized in Table . To provide consistency with the experimental method, the selection of entrainment data has been restricted to those measured at the abrupt gas exit of the bubbling fluidized bed with the steady-state recirculating system shown in the description by Kunii and Levenspiel . The column diameter ( D t ) was considered as the hydraulic diameter for the fluidized bed of George and Grace …”

Bulk-Density Distributions of Solids in the Freeboard of a Gas-Solid Fluidized Bed

“…Nevertheless, relatively little has been done to theoretically interpret or mechanistically model the experimental data. By postulating the existence of three distinct phases in the freeboard, i.e., gas stream with completely dispersed solids, ascending agglomerates of particles, and descending agglomerates of particles, Kunii and Levenspiel (1969) have derived an expression for the solids holdup in the freeboard. Horio et al ( 1980) have proposed a model for particle transport by assuming that the motion of the particles is Brownian.…”

An examination of ash elutriation from a fluidized bed regenerator

“…Within the reactor, a portion is filled with bed particles, while the remainder is left vacant. The column height above the bed of particles is referred to as the "freeboard height" [6].…”

“…This results from the fact that a larger freeboard height provides sufficient distance for gravity to counteract particle velocity. The freeboard height at which gravity neutralizes the elutriated particle velocity is defined as the Transport Disengagement Height (TDH) [6]. This is a critical design characteristic, and can be determined through experimentation with a specific bed material.…”