(504d) Dense Membrane Contactors for Physical Solvents Regeneration: Proof of Concept Study and Modeling

E. CHABANON, D. ROIZARD, E. FAVRE*

E-mail: eric.favre@ensic.inpl-nancy.fr

Membrane contactors have received increased attention for several years and are already used in different industrial applications, particularly for intensified gas liquid processes. Studies and applications are almost systematically based on microporous hydrophobic membranes. In that case, the achievement of non wetting conditions on long term range imposes the use of a liquid phase with a high surface tension, such as aqueous solutions. Consequently, low surface tension liquids, such as physical solvents, cannot be used. This study intends to explore the potentialities of dense asymmetric polymeric hollow fibers as membrane contactors for physical solvents applications. In that case, theoretical computations show that promising performances could be obtained, due to the possibility to simultaneously sustain a high transmembrane pressure (thanks to the dense skin layer which is not subject to wetting pressure limitations) and offer high mass transfer coefficients. A case study, dissolved carbon dioxide removal from a physical solvent (NMP), has been investigated at lab scale with a module based on PPO hollow fibers. Solvent regeneration by depressurization has been investigated and several operating parameters have been studied and modeled (pressure difference, solvent flowrate, CO₂ solubility). It will be shown that the concept offers attractive performances, especially with regard to the possibility to maintain the liquid under high pressure conditions, contrarily to flash drums which are classically used for physical solvents degassing operations. The improvement in terms of energy efficiency of the regeneration process based on this peculiarity (no liquid recompression step on the solvent loop) will be addressed. Several applications of the concept at industrial scale will be discussed.