Computational fluid dynamics study of gas-liquid mass transfer in concentric tube airlift reactor with helical baffle

Abstract

This work aims to understand the effect of stationary and rotational helical baffle on gas-liquid mass transfer in concentric tube airlift reactor. A computational fluid dynamics (CFD) method is conducted, and the predicted of overall volumetric mass transfer coefficient (KLa) in concentric tube airlift reactor (0.29 m diameter and 1.5 m initial liquid height) without baffle is validated reasonable agreement with the empirical equations reported in the literatures. The results were simulated basing on this validated model. It indicated that the helical baffle with the same width of riser (40 mm) could increase the KLa by 132∼202% at the superficial gas velocity of 0.00212 m·s−1 when compared with that the airlift reactor without baffle. At the width of helical baffle less than width of riser, the KLa decreased with the decreasing of the width (W) and the rotational speed (n) of helical baffle. When the width of stationary helical baffle is 30 mm, the effect of helical baffle on enhancing mass transfer is negligible. In addition, the KLa decreased with the increasing of the helix pitch (H) of helical baffle and the distance of the lower edge of helical baffle from the bottom of reactor (L).