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Detecting regime transitions in slurry bubble columns using pressure time series
Author(s) -
Ruthiya Keshav C.,
Chilekar Vinit P.,
Warnier Maurice J. F.,
van der Schaaf John,
Kuster Ben F. M.,
Schouten Jaap C.,
van Ommen J. Ruud
Publication year - 2005
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.10474
Subject(s) - bubble , standard deviation , slurry , mechanics , transition point , series (stratigraphy) , flow (mathematics) , constant (computer programming) , analytical chemistry (journal) , physics , chemistry , thermodynamics , mathematics , geology , statistics , chromatography , paleontology , computer science , programming language
Abstract Changes in the coherent standard deviation and in the average frequency of measured pressure time series with gas velocity, are proposed, as unique and unambiguous criteria to mark flow regime transitions in slurry bubble columns. In a 2‐dimensional (2‐D) slurry bubble column, pressure time series are measured at different gas velocities simultaneously with high‐speed video recording of the gas‐liquid flow. The frequency of occurrence and the average diameter of the large bubbles are determined from video image analysis. The gas velocity where the first large bubbles are detected, with an average diameter of 1.5 cm, and with a frequency of occurrence of one bubble per s, is designated as the first regime transition point (transition from the homogeneous regime to the transition regime). At this point, the coherent standard deviation of the measured pressure fluctuations clearly increases from zero. The gas velocity where the average diameter and the frequency of occurrence of the large bubbles become constant, is designated as the second regime transition point (transition from the transition regime to the heterogeneous regime). From this point onward, the slope of the coherent standard deviation of the measured pressure fluctuations clearly decreases with gas velocity, while the average frequency becomes constant. These clear changes with gas velocity in the coherent standard deviation, and in the average frequency are also demonstrated in a 3‐D slurry bubble column. © 2005 American Institute of Chemical Engineers AIChE J, 2005