(186c) Pulsing to Improve Bubble Column Performance - Jetting Gas Rates

The liquid phase of a batch bubble column was subjected to low amplitude pulsations at modest frequencies (range 0-30 Hz). At jetting gas rates (15 to 30 ml/sec) using a single injector tube we found that substantial bubble breakage occurred in the column proper at frequencies below 30Hz. Two piston types were used, a flexible rubber membrane, and a modification thereof to cause a more rigid, stiff piston behavior. The mass transfer performance differences between the piston types were quite remarkable, the former yielding peaking with respect to increased frequency, and the latter produced monotonic increases up to an asymptote as frequency was increased. The stability theory of Benjamin and Ursell was found useful in tracking regimes of maximum enhancement.