Engineering evaluation of CO2 separation by membrane gas separation systems

Abstract

The possible application of membranes for CO2 separation in the treatment of non-valuable streams (e.g.,flue gas of a power plant or cement industry) or valuable streams (e.g., biogas) has been analyzed. Someselection criteria useful in the choice of membrane gas separation for CO2 capture are discussed toevaluate the advantages potentially offered by membrane systems. Membrane selectivity ranging from30?50 (values of commercial membranes) to 100?500 (values of most promising laboratory membranes)and different feed/permeate pressure ratios were considered for the various cases. The composition andrecovery of carbon dioxide in the membrane-treated stream were the target parameters taken intoaccount as guidelines in the evaluation of the separation technology performance. General “maps” of CO2permeate concentration versus CO2 recovery have been developed by means of a simple tool that takesinto account the influence of the most important parameters affecting the membrane systemperformance (that is, membrane selectivity and permeation driving force). The analyses indicated thatthe separation depends on various interrelated factors: the membrane material (selectivity and flux), theoperating conditions (pressure ratio), and the final requirements (CO2 recovery and composition). Also,the operational limit and the potentialities of the membrane gas separation technology were analyzedunder these conditions. The “maps” proposed and utilized for CO2 separation are valid and can beutilized for other gas separations in which the membrane shows selectivities similar to those taken intoaccount here.