Advances in characteristics analysis, measurement methods and modelling of flow dynamics in airlift reactors

Airlift reactor (ALR) is a gas-liquid contact apparatus widely used in industrial applications due to its simple design, absence of moving parts and relatively low energy consumption. This circumstance intensified the studies in ALR applications for the past decades mainly covering characteristics analysis of flow dynamics, measurement methods development, and flow simulation for various geometries and operational conditions. Retrospect of the flow dynamics characteristics in ALRs were carried out from different sections of the typical ALRs, and studies about transformation of flow regimes and various driving forces of the reactor had been summarized. Discussed flow measurement methods mainly include documented methods for bubble sizes and their distribution, mixing time, local or total gas holdup and average or local liquid velocity. Numerical simulation method for flow process in ALRs are also reviewed, which are classified into two series, i.e. mathematical mechanism models and CFD models. Hereinto, CFD modeling methods are analyzed in emphasis which involving framework model for multiphase flow, bubble descriptions and accessible closure relationships. The review provides a comprehensive analysis of such efforts, with critical discussion of published standpoints.