The influence of gas inlet design on gas hold-up values for water and various solutions in a loop-type air-lift fermenter
| Autor: | D. A. John Wase, W.J. McManamey, S. Raymahasay, K. Thayanithy |
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| Rok vydání: | 2008 |
| Předmět: | |
| Zdroj: | Journal of Chemical Technology and Biotechnology. Biotechnology. 34:151-164 |
| ISSN: | 1935-1828 0264-3421 |
| DOI: | 10.1002/jctb.280340303 |
| Popis: | Gas hold-up was measured in an external loop air-lift fermenter for air in water, in sodium chloride and sodium sulphate solutions (concentrations between 0.025 and 1.0 kmol m−3), in glucose solutions (0.025 to 0.25 kmol m−3), sodium carboxymethyl cellulose (CMC) solutions (0.1, 0.2 and 0.5 mass %) and in suspensions of cellulose powder in water. Gas superficial velocities were up to 0.03ms−1. Two types of gas spargers were used: one had six holes each of 1.6mm diameter, the other was of porous metal, which produced very small bubbles. Porous metal spargers with different diameters were also used, to alter the fraction of the cross-sectional area of the riser which was aerated (the ‘fractional aerated area’). The use of dimensionless gas velocities, obtained by dividing the superficial gas velocities by a characteristic velocity for each of the non-Newtonian liquids and solid suspensions, made possible a general correlation between gas hold-up, dimensionless gas velocity and the fractional aerated area, in bubbly flow conditions. The characteristic velocities for the electrolyte solutions could be related to the concentrations of the electrolytes. No general correlation could be obtained for gas slug-flow conditions, although theoretically-based relationships represent the results for each liquid. Gas slug-flow was observed for the non-Newtonian CMC solutions for most of the gas rates used at the lower concentrations; only at the highest concentration was bubbly flow found over a wide range of gas rates. |
| Databáze: | OpenAIRE |
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