Gas- Liquid Flow Hydrodynamics and Mass Transfer in Micro-Packed Beds

In this paper, the hydrodynamics and gas-liquid mass transfer characteristics of gas-liquid two-phase flow in the micro-packed bed were investigated. The hydrodynamics, including pressure drop, residence time distribution and liquid holdup were determined. The effect of gas and liquid superficial velocity, glass bead size, packed bed diameter and liquid property on the hydrodynamics has been studied. The results showed that the pressure drop and liquid holdup in micro-packed beds were higher than that in conventional packed beds due to the effect of capillary pressure. A mathematical model has been developed to describe the hydrodynamics in the micro-packed beds by taking into account the capillary force. The volumetric liquid-side mass transfer coefficients (k_La) was evaluated by the chemisorption of CO₂ in methyl diethanolamine water solution. An online measurement method was developed with in-line FTIR, which was used to measure bicarbonate ion concentration to calculate CO₂ absorption rate. The influence of gas and liquid superficial velocities, packed bed size and packing particle size on the k_La was examined. The results showed that k_La was in the range of 0.24~0.7 s^-1, which is about an order of magnitude than that of conventional trickle bed. An empirical correlation was developed to predict the k_La at different conditions.