Mass transfer in gas-fluidized beds: measurement of actual driving forces

Abstract

Concentration profiles of naphthalene vapors were measured in the flow of air through fluidized beds of naphthalene spheres. Seven different sizes of spheres were used in this study and ranged from 0.02480 to 0.2000 cm. To avoid saturation conditions in the air leaving the bed, the naphthalene spheres were diluted in a matrix of inert beads (styrene divinylbenzene copolymer) of the same size and density as the naphthalene spheres. The established concentration profiles were graphically integrated to produce from them actual mass transfer coefficients. These transfer coefficients were then used to calculate j d, mass transfer factors, for this fluidized bed system and also the product j d Re f which has been found to depend on Re mf , the corresponding Reynolds number at minimum fluidization conditions. Actual driving forces, (Δ p) a were normalized with the corresponding log-mean values, (Δ p) m , to produce the driving force factor, F = (Δ p) a /(Δ p) m . This factor has been correlated with the parameters of the system and can be predicted with a certainty of 10.5%.