3‐D Simulations of an Internal Airlift Loop Reactor using a Steady Two‐Fluid Model

Abstract

Three-dimensional (3-D) simulations of an internal airlift loop reactor in a cylindrical reference frame are presented, which are based on a two-fluid model with a revised k-e turbulence model for two-phase bubbly flow. A steady state formulation is used with the purpose of time saving for cases with superficial gas velocity values as high as 0.12 m/s. Special 3-D treatment of the boundary conditions at the axis is undertaken to allow asymmetric gas-liquid flow. The simulation results are compared to the experimental data on average gas holdup, average liquid velocity in the riser and the downcomer, and good agreement is observed. The turbulent dispersion in the present two-fluid model has a strong effect on the gas holdup distribution and wall-peaking behavior is predicted. The CFD code developed has the potential to be applied as a tool for scaling up loop reactors.

Investigation of hydrodynamics and transition regime in an internal loop airlift reactor using CFD

“…Because of the high turbulent kinetic energy near the draft tube wall, the gas holdup is also high. This finding confirms the numerical results of Huang et al (2007). Furthermore, the gas bubbles flow from the downcomer to the riser by moving up the bulk liquid near the wall.…”

“…Computational fluid dynamics (CFD) has emerged as an effective tool to investigate gas-liquid ILALRs hydrodynamics Oey et al, 2001;Blazej et al, 2004a;Talvy et al, 2007;Huang et al, 2007). Mudde and van den Akker (2001) simulated an ILALR under steady state conditions at low superficial gas velocities using a two-fluid model (TFM).…”

“…Investigating scale up effects, they found a significant increase in the liquid recirculation and a considerable reduction in the gas holdup. Huang et al (2007) developed a two-fluid model by considering a revised k-ε turbulence model. Their model was applied for simulation of two-phase bubbly flow inside an internal airlift loop reactor at full 3D framework in the steady-state.…”

Sensitivity Study on Modeling an Internal Airlift Loop Reactor Using a Steady 2D Two‐Fluid Model

“…Different papers adopted different formulations even for the same configuration, e.g., by van Baten et al [2] and Huang et al [3]. Since the experimental information available to date is insufficient to unambiguously determine the drag coefficient, the literature abounds with various forms of correlation.…”

“…Mudde et al [8] and Huang et al [3] simulated the internal airlift loop reactor (IALR) using a steady two-fluid model and in the majority of research, the IALR was simulated using the dynamic model to avoid numerical divergence. However, the steady model requires the terminal slip velocity normal to the outlet boundary and both papers prescribed a fixed velocity of 0.2 m/s.…”