Oxygen transfer and mixing in a tower cycling fermentor

Abstract

SummaryTower cycling fermentors for the production of single-cell protein from volatile substrates were studied. The mass transfer, mixing and circulation patterns, and residence time distribution (RTD) curves were investigated in these vessels. This study suggests that the tower cycling fermentors for volatile substrates fermentation may improve product yields and a t the same time reduce the power consumption, thereby resulting in a significant increase in operating cost savings and capital profits. The results of this research further indicate a future potential for commercial scale tower cycling fermentors.

Circulation liquid velocity, gas holdup and volumetric oxygen transfer coefficient in external‐loop airlift reactors

“…Estimated values of Ed by eqn ( 5 ) agreed relatively well with the experimental values of Ed. The riser linear liquid velocity data were well correlated by eqn (6). BelloZ4 theoretically derived a dependence of the riser linear velocity on the cube root of the riser superficial gas velocity.…”

Liquid circulation and mixing characteristics of airlift contactors

“…The mixing time, the time taken following a concentration disturbance to achieve a certain degree of homogeneity in the liquid phase, is particularly important for consideration of the contactor as a mixer, e.g., fed-batch reactors or batch and fed-batch fermentors. Lin et al (1976) and Blenke (1979) have related the relative mixing time (i.e., the ratio of the mixing time to the circulation time, t,,,/r<) to the fractional approach to the final tracer concentration, 6. Their respective expressions are given by Equations ( 3 ) and (4) In this work, l,,/r< is reported and related to a more fundamental physical parameter of the contactor, i.e., A,/A,.…”

Gas hold-up in non-newtonian solutions in a bubble column with internals

“…It is generally accepted that the rheological behaviour of such systems can be reasonably simulated by the solutions of carboxy-methyl cellulose (CMC), To design such reactors effectively, knowledge of gas hold-up is essential. A good amount of work on this aspect (Nishikawa et al, 1977;Nakanoh and Yoshida, 1980;Shah et al, 1982;Godbole et al, 1984) has given rise to several modifications of conventional bubble column (Lin et al, 1976;Young et al, 1987). However, in commercial bubble columns using non-Newtonian solutions, the internal obstacles in the form of heat exchanger, instrumentation probes, downcomers and risers are normally used.…”