Effect of liquid on interparticle forces in gas‐fluidized beds

Abstract

In an investigation of the behavior of an air‐fluidized bed of glass spheres under varying interparticle forces, the results obtained are explained by hypothesizing the coexistence of particulate and aggregative fluidization. As interparticle forces are increased, a greater portion of the particles are in aggregative fluidization, resulting in a decrease in bed height. In this study water added to the fluidizing air increased the interparticle forces. Up to 0.5 mass % water was used, with a fluidized bed of glass spheres 0.013 to 0.035 in. in diameter. The resulting decrease in bed height has been correlated by means of a theoretical equation for the increase in interparticle forces due to the added water.

A kinetic study of plutonium dioxide dissolution in hydrochloric acid using iron (II) as an electron transfer catalyst

“…As with bulk dry-powder mixing, interparticle forces was found to promote aggregation of fine particles (~7 0 pm), prevent their uniform dispersion, and result in channeling and 48 excessive entertainment in the off gas stream. The forces attributed to the cohesion of fine particles included van der Waals forces (Rumpf 1962, Baerns 1966, Chaouki et al 1985, Bowling 1988, Visser 1989, Lam and Newton 1992, Baeyens 1992; electrostatic attraction (Rumpf 1962, Derjaguin et al 1968, Bailey 1984, Briens et al 1992; fluid bridges (Parker andStevens 1959, Rumpf 1962); and a general crystallization or precipitation phenomena (Geldhart et al 1984, Kono 1987). …”

Studies of Fluidization of Moist Particles

“…Therefore, the abnormal behavior of silica sand may be attributable to surface roughness rather than the composition of the sand, but it still needs more detailed investigation. Figure 9 shows the measured value of JPS for silica sand of Z)p*=0.36mm as a function of the gas velocity ug with the moisture content (w) as a param- ipfl= J80^ugLfiF (l-ec)2 (6) where ec and L denote the mean void fraction and the bed height of the fixed bed, respectively. It is seen that the observed values can be approximated by Eq.…”

Heat transfer in fluidized beds of flour and starch

“…The difficulty is due to the interparticle forces which are believed to be greater than the forces exerted on the particles by the fluidizing gas (43). The action of interparticle forces causes agglomeration of particles, and bridging between such agglomerates.…”