Mixing parameters for an airlift bioreactor considering constant cross sectional area of riser to downcomer: Effect of sparging gas location

Abstract

The effect of mode of sparging gas on the mixing parameters of an internal loop airlift bioreactor was investigated. Two bioreactors of identical volume of 14×10 3 cm 3 and the optimum riser to downcomer cross sectional area ratio of 0.6 were studied. In one bioreactor a gas sparger was located in the draft tube and in the annulus in another. Liquid mixing characteristics, i.e., mixing time and circulation time, were employed to describe the performance of the bioreactors. The tracer injection method was used to determine the mixing parameters. A mathematical modeling based on the tanks-in-series model was employed to characterize the hydrodynamics behavior of the bioreactors. Matlab 7.1 software was used to solve the model equations in the Laplace domain and determine the model parameter, the number of stages. A comparison between the simulation results and experimental data showed that the applied model can accurately describe the behavior of the bioreactors. The results showed that when the gas sparger was located in the draft tube, the liquid mixing time, circulation time, and the number of stage were less than while the gas sparger was located in annulus. This is due to more wall effects, more energy losses and pressure drop in the case of gas injection in the annulus.

Research on Mass Transfer Coefficient Measurement Model of External-Loop Airlift Reactor

“…The airlift reactor has become one of the most promising devices in the chemical, biochemical and environmental engineering realms [1,2]. Its main advantages over other conventional reactors include the excellent contact among the different phases, ease of particles removal or replenishment, and high heat and mass transfer rate [3]. The higher gas-liquid contact area and the favorable flow pattern of this kind of reactors are very attractive.…”