Turbulent Properties in Bubble-Flow Region in External-Loop Airlift Bubble Column

• Published in: JOURNAL OF CHEMICAL ENGINEERING OF JAPAN Vol. 26; no. 6; pp. 637 - 643
• Main Authors: Okada, Kenji, Shibano, Shinji, Akagi, Yasuharu
• Format: Journal Article
• Language: English
• Published: Tokyo The Society of Chemical Engineers, Japan 1993; Society of Chemical Engineers; Taylor & Francis Group
• Subjects: Airlift Bubble Column; Applied sciences; Bubble Size; Chemical engineering; Eddies; Exact sciences and technology; Flow Model; Gas-Liquid Two-Phase Flow; Multiphase flow; Power Spectrum; Reactors; Turbulence Structure; Gas liquid; Particle size; Two phase flow; Turbulent flow; Theoretical study; Velocity distribution; Experimental study; Modeling; Bubble; Bubble column; Gas liquid flow; Air lift; Reactor; Power spectrum
• ISSN: 0021-9592; 1881-1299
• DOI: 10.1252/jcej.26.637

Turbulent properties of the bubble flow region in an airlift bubble column were examined using an anemometer for water and CMC solutions. The turbulent structures of the gas-liquid system in these liquids were evaluated by the power spectrum of turbulent eddies. The power spectrums of the liquids decayed with decrease in the size of eddies with a slope of –5/3 to –2. This is almost comparable to that of Kolmogoroff’s spectrum law for an isotropic turbulence. The radial distributions of turbulent intensity, u′l, macro-scale of turbulent eddies, Λf, bubble diameter, dB, and bubble rise velocity, uB, were measured. The influence of the media on these properties was examined. The turbulent viscosity, νt, was evaluated from the values of u′l, and Λf for the liquids. It was found that νt of gas-liquid two-phase flow was five times higher than that of a single-phase flow of water. Using these turbulent properties, the liquid superficial velocity, UL, slip velocity of bubble, uBS, and bubble diameter (Sauter diameter), dBS, in the riser were estimated theoretically. The estimated values agreed with those obtained experimentally.