Evaluating the intensification potential of membrane contactors for gas absorption in a chemical solvent: A generic one-dimensional methodology and its application to CO2 absorption in monoethanolamine
Résumé
A generic one-dimensional model was developed, leading to a better comprehension of the intensification potential of hollow fiber membrane contactors for gas absorption in a chemical solvent. The methodology was applied to an illustrative case study, namely the chemical absorption of CO2 in industrially relevant operating conditions for post-combustion capture. These conditions introduce numerous constraints, thereby leading to an estimate of the dimensions of the hollow fiber membrane contactor as a function of its geometrical characteristics. In the parametric range that was considered, the flow regime is laminar, and the concentration profiles are fully developed both for the gas and liquid flows that lead to mass-transfer coefficients that are independent of the flow velocities. The influence of the external fiber radius and the membrane permeability and thickness on overall process performance are clearly evident. Liquid flow around the fibers that proceeds with gas flowing through the lumen of the fibers is shown to be particularly effective. Under favorable conditions (i.e., an external fiber radius of 2 × 10−4 m and sufficient membrane permeability), the overall contactor volume can be divided by a factor of approximately twenty relative to the volume of an absorption column. Under these conditions, the superficial gas velocity can be maintained at a high level (i.e., greater than 1 m s−1) with a drop in gas and liquid pressure of only approximately 50 mbar.