CFD simulation of internal-loop airlift reactor using EMMS drag model

Abstract

The simulation of internal-loop airlift reactors is challenging because complex meso-scale structures exist in different sections of the reactor, separated by the draft tube. This paper reports on the computational fluid dynamics (CFD) simulation of internal-loop airlift reactors using a new drag model derived from the dual-bubble-size (DBS) model, an extended energy-minimization multi-scale (EMMS) approach for gas–liquid flows. Compared with the traditional Schiller–Naumann (S–N) correlation, the new model improves the simulation of gas holdup in the riser and downcomer significantly. In particular, gas holdup and circulation of two-phase flow can be modeled successfully using the new model, whereas traditional drag models such as the S–N correlation show an absence of gas in the downcomer. The simulation demonstrates the advantage and potential of this new model for internal-loop airlift reactors.