Identification of Various Transition Velocities in a Bubble Column Based on Kolmogorov Entropy
The Kolmogorov entropy (KE) algorithm was applied successfully to gas holdup fluctuations measured in a 0.102 m I.D. stainless steel bubble column equipped with a perforated plate distributor (19 holes ∅︁ 1 mm). Nitrogen was used as the gas, while both 1‐butanol and gasoline were used as liquids. 1‐...
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Veröffentlicht in: | Chemical engineering & technology 2007-04, Vol.30 (4), p.534-539 |
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Sprache: | eng |
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Zusammenfassung: | The Kolmogorov entropy (KE) algorithm was applied successfully to gas holdup fluctuations measured in a 0.102 m I.D. stainless steel bubble column equipped with a perforated plate distributor (19 holes ∅︁ 1 mm). Nitrogen was used as the gas, while both 1‐butanol and gasoline were used as liquids. 1‐Butanol was aerated at pressures, P = 0.1 and 0.5 MPa, whereas gasoline was aerated at P = 0.1 and 0.2 MPa. Based on the peaks in the KE values under the pressures examined in both liquids, the boundaries of the following five regimes were identified: bubbly flow, first transition, second transition, coalesced bubble (4‐region flow) and coalesced bubble (3‐region flow). As the pressure increases to P = 0.5 MPa in 1‐butanol, all four transition velocities shift to higher superficial gas velocity, uG. In addition, in gasoline at P = 0.2 MPa and uG ≤ 0.017 m s–1, the existence of a chain bubbling regime was detected, whereas in 1‐butanol at P = 0.5 MPa and uG ≤ 0.02 m s–1, both laminar and turbulent chain bubbling subregimes were identified. It was found that in 1‐butanol under ambient pressure, the second and fourth transition velocities occur earlier than in gasoline.
The bubble column performance can be significantly affected by the different flow regime transitions. Since reactor volume productivity, mass transfer, heat transfer and mixing are affected by the prevailing flow regime, it is very important to establish a reliable identification method. |
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ISSN: | 0930-7516 1521-4125 |
DOI: | 10.1002/ceat.200600344 |