Gas–liquid mixing in the stirred tank equipped with semi-circular tube baffles

Abstract

Despite extensive contributions have been made over the past several decades, there are still ongoing challenges in improving gas dispersion performance in stirred tanks. To that end, a stirred tank equipped with four semi-circular (SC) tube baffles was designed. Hydrodynamics in the stirred tank before and after aeration were studied. The turbulent fluid flow was simulated using the standard k-ε turbulence model. The gas–liquid two-phase flow was simulated by the Eulerian–Eulerian multiphase model and the k-ε dispersed turbulence model. The impeller rotation was modeled with the multiple reference frame (MRF) approach. Firstly, the grid independence test was made. By comparing the distributions of gas holdup in the flat-plate (FP) baffled stirred tank with literature results, the reliability of the numerical model and simulation method was verified. Subsequently, the flow field, gas holdup and power consumption of the SC and FP configurations were studied, respectively. Results show that the former can increase the fluid velocities and promote the gas holdup dispersion. Besides, it is energy-saving and has a higher relative power demand (RPD). The findings obtained here lay a preliminary foundation for the potential application of the SC configuration in the process industry.

Numerical Simulation of Flow Field in Pulper Cavity

“…It can be seen from the simulation results that the turbulence intensity increases, the order and symmetry results disappear after adding the spoiler. That is to say, the radial circulation disappearance can increase the collision times between materials, material and cutter, material and cavity, and improve the pulping rate [13] . The turbulent kinetic energy data are listed in Table1 below.…”