Enzyme-mediated CO2 capture in oscillating structured packed-bed columns - Hydrodynamics and process performance for offshore applications

Abstract

Gas-liquid countercurrent flow dynamics and enzymatic CO2 hydration performance in vertical, inclined, and oscillating structured packed-bed columns were explored via an unsteady-state 3-D model with the intent to understand the conduct of packed-bed columns under offshore conditions. A significant asymmetric countercurrent gas-liquid flow is established at larger structured packed-bed column permanent inclinations inducing noticeable liquid accumulation in lowermost cross-sectional area of the column. On the contrary, in marginally inclined structured packed-bed columns only a reduced fraction of liquid is subject to gravity-driven migration in circumferential and radial directions. Symmetrical externally-generated column oscillations give complex secondary flows in radial and circumferential directions resulting in oscillatory patterns around steady-state solution of vertical column position with the amplitude and propagation frequency influenced by the column sinusoidal angular motion. Inclined structured packed-bed columns underperform the vertical configuration for both enzymatic CO2 hydration processes with immobilized and solution-borne carbonic anhydrase. An oscillatory CO2 hydration performance around the steady-state solution of vertical column, affected by the parameters of angular motion of reactor, is generated by the symmetrical externally-induced reactor periodic oscillations. Though requiring a considerable amount of enzyme, CO2 removal efficiency is superior for the hydration process with solution-borne enzyme regardless of column configuration because of absence of diffusion within enzyme washcoat.