A gas distributor capable of multiple injection directions to improve the gas–liquid dispersion performance in the airlift loop reactor

Abstract

As the gas supply equipment, the gas distributor is one of the core components in the airlift loop bioreactor. The gas injection direction and the dynamic behavior of the bubbles significantly affect the gas–liquid dispersion performance in the bioreactor. Therefore, based on the previously designed airlift loop reactor, a new type of tubular convex gas distributor (TCD) with multi-angle gas injection capability was developed. Under the conditions of different superficial gas velocities, the gas–liquid flow in the reactor was numerically simulated by computational fluid dynamics. The results showed that TCD had better gas–liquid dispersion and mass transfer performance in this reactor than several other traditional types of distributors. Under the experimental conditions, the optimal gas–liquid two-phase flow in the reactor was observed when the angle of the TCD vent tube was 15°, the number was 12, and the diameter was 1 mm. It was found that the error between the experimental results and the simulation results was controlled within 10 %, which verified the accuracy of the simulation. The application of TCD in the airlift loop bioreactor improved the wastewater treatment and biomass accumulation, significantly. The TCD can provide design ideas for gas distributors in other types of bioreactors, and is beneficial to improving the process of biological wastewater treatment for industrial application.