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Pulsing to improve bubble column performance: I. Low gas rates
Author(s) -
Knopf F. Carl,
Ma Jia,
Rice Richard G.,
Nikitopoulos Dimitris
Publication year - 2006
Publication title -
aiche journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.958
H-Index - 167
eISSN - 1547-5905
pISSN - 0001-1541
DOI - 10.1002/aic.10698
Subject(s) - breakup , bubble , injector , mechanics , amplitude , volumetric flow rate , materials science , chemistry , physics , thermodynamics , optics
The liquid phase of a batch bubble column was subjected to low‐amplitude pulsations at modest frequencies (range 0–30 Hz). At low gas rates (up to 5 mL/s) using a single‐injector tube we found that substantial bubble breakage occurred at frequencies < 30 Hz. At the low flow rates examined, enhanced bubble breakup occurred mainly as a result of two‐phase flow developing within the injector tube. External sinusoidal pulsation caused high‐velocity water ingestion (suck‐back) and expulsion from the injector. This suck‐back action caused intense fragmentation of gas slugs within the injector, often into many very small bubbles, as high‐speed imaging showed. Mass transfer coefficients were measured as a function of pulsation frequency and driver amplitudes at several air flow rates, demonstrating the benefits of this type of pulsed bubble column. A simple dynamic mechanical model of the pulsed liquid column predicted resonance, which depended on membrane thickness of the driving piston. © 2005 American Institute of Chemical Engineers AIChE J, 2006