Abstract: In order to evaluate the practical effect of annular gas distributor applied in airlift loop bioreactor, this paper studied the structure optimization of annular gas distributor and investigated the effects of opening direction, diameter and installation height of gas distributor on mass transfer performance. Meanwhile, it measured the performance parameters of the optimized annular gas distributor, such as oxygenation capacity, oxygen utilization ratio and power efficiency. The results showed that the oxygen mass transfer coefficient of the bioreactor was the best when the opening direction of gas distributor was 30° horizontally downward, the diameter was 0.5R and the installation height was 0.5R (R is the radius of the reactor guide shell) simultaneously. The results also indicated that the suitable gas rate was 2 m³/h, and at this point, the oxygenation capacity (O₂) was 0.14 kg/h with oxygen utilization ratio 26.03% and dynamic efficiency 2.52 kg/(kW·h).

Key words: loop reactor, structure optimization, opening direction, diameter, installation height, oxygen mass transfer coefficient