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Large Bubble Sizes and Rise Velocities in a Bubble Column Slurry Reactor
Author(s) -
Vandu C.O.,
Koop K.,
Krishna R.
Publication year - 2004
Publication title -
chemical engineering and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.403
H-Index - 81
eISSN - 1521-4125
pISSN - 0930-7516
DOI - 10.1002/ceat.200402126
Subject(s) - bubble , slurry , coalescence (physics) , volume (thermodynamics) , porosity , analytical chemistry (journal) , materials science , mechanics , homogeneous , bubble point , superficial velocity , volumetric flow rate , bubble column reactor , chemistry , chromatography , thermodynamics , flow (mathematics) , composite material , gas bubble , physics , astrobiology
The results are reported of an experimental study of the gas holdup, ϵ G , large bubble diameter, d Lb , and large bubble rise velocity, V Lb , in a 0.1 m wide, 0.02 m deep and 0.95 m high rectangular slurry bubble column operated at ambient temperature and pressure conditions. The superficial gas velocity U was varied in the range of 0–0.2 m/s, spanning both the homogeneous and heterogeneous flow regimes. Air was used as the gas phase. The liquid phase used was C 9 ‐C 11 paraffin oil containing varying volume fractions (ϵ S = 0, 0.05, 0.10, 0.15, 0.20 and 0.25) of porous catalyst (alumina catalyst support, 10 % < 10 μm; 50 % < 16 μm; 90 % < 39 μm). With increasing slurry concentrations, ϵ G is significantly reduced due to enhanced bubble coalescence and for high slurry concentrations the “small” bubbles are significantly reduced in number. By the use of video imaging techniques, it was shown that the large bubble diameter is practically independent of the gas velocity for ϵ S > 0.05 and U > 0.1 m/s. The measured large bubble rise velocity V Lb agrees with the predictions of a modified Davis‐Taylor relationship.