Channeling in packed columns

Abstract

Experiments on the displacement of sugar liquors by water from columns of granular bone charcoal (sweetening off) have led to a theory which accounts for the channeling which sometimes occurs when one fluid follows another along a uniformly packed column. The existence or absence of a tendency towards channeling is shown to depend upon the linear velocity of flow. A critical velocity can be defined in terms of the viscosities and densities of the two fluids. The interface between the two fluids may be (1) inherently stable, (2) inherently unstable, (3) stable or unstable according to the relation between the actual and the critical velocities. In the case of "sweetening off"-an important operation in sugar refining-channelling occurs if the velocity of flow exceeds the critical velocity. Experimental evidence is quoted in support of the theory. © 1952.