| Abstrakt: |
A simple analysis of bubble column hydrodynamics indicates that the upper limit of the homogeneous flow regime is the optimum operating condition for solvent sublation. This is in contrast to the traditional belief that solvent sublation is limited to the string bubbling flow regime. The implication is that the limited number of low-pressure adsorptive processes that operate in the bubbly flow regime, such as solvent sublation, may soon become viable options for industry. Results of gas holdup, bubble size, and dispersion experiments are reported as functions of gas velocity for three different types of gas-bubble spargers, namely, a fine porous glass frit, a flexible rubber membrane, and an annular shear sparger. The data show that the shear sparger affects the column dynamic properties such that the transition to the heterogeneous regime is delayed. Therefore, for applications requiring homogeneous flow, column capacity can be improved by approximately 25%. Moreover, the interfacial area produced by the shear sparger operating in the homogeneous regime rivals that produced by perforated and sintered plates operating in the heterogeneous regime. |
