Abstract A distributed parameter model for an airlift fermentor is presented. A riser represents the airlift fermentor, with plug flow in both gas and liquid phases, a well‐mixed section that acts as gas separator, and a downcomer with plug flow. The set of equations proposed makes possible both the understanding and design of the system. Macroscopic balances shows a behavior that is very close to conventional continuous stirred tank fermentor from the viewpoint of biomass production. In addition, the model predicts concentration profiles of biomass, substrate and oxygen in the liquid, and oxygen in the gas phase. This allows estimation of optimal gas flow rate for sufficient oxygen transfer with minimum energy input.
Abstract A previously presented model for an airlift fermentor is extended by considering the variations of pressure along the tubes. The fluid dynamics of the system is represented with the acid of correlations obtained from experiments. Only oxygen concentrations are considerations are considered. The influences of the various parameters affecting the system are analyzed. The model allows prediction of oxygen concentrations in the different points of an airlift fermentor and calculation of the best values of the gas flow rate.
Abstract Measurements of local hold‐up and liquid recirculation rate in an air‐lift reactor were performed with two types of gas spargers using a manometric technique. A simple exponential function correlated properly the liquid velocity measured to the gas flow rate. The local hold‐up varied appreciably along the column and showed a maximum in most of the cases. A simple linear relationship correlated the local gas velocity with the total flow rate of the mixture.
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