GAS-SOLIDS MIXING AND HEAT TRANSFER STUDIES IN INCIPIENTLY FLUIDIZED BEDS OF NONUNIFORM CROSS-SECTIONAL AREA

Solids mixing and heat transfer studies were performed in a nonuniform cross-section fluid bed at incipient fluidization conditions. The solids mixing studies were performed at isothermal conditions to determine if incipient fluidization conditions could be achieved in a 4-foot deep variable cross-section bed, and if solids flow patterns existed significantly different from that of a constant cross-sectional area bed. The solids flow characteristics approached plug flow conditions, allowing possible countercurrent multistage operation of a tapered fluid-bed reactor. Heat transfer studies at incipient fluidization conditions indicated heat transfer capabilities comparable to fixed-bed systems. Heat transfer coefficients ranging from 2 to 15 B.t.u./hr.-sq. ft.-° F. were found for the transfer of heat between an internal heating element and the bed. An insert design equation was developed for the construction of fluid bed inserts to allow incipient fluidization to exist across the entire depth of the bed at steady-state heat transfer conditions. © 1969, American Chemical Society. All rights reserved.