A hybrid process combining oxygen enriched air combustion and membrane separation for post-combustion carbon dioxide capture

For carbon dioxide capture and storage (CCS), similar to a large majority of industrial processes, the separation (i.e. capture) step dominates the costs of the technological chain. Based on a concept of minimal work of concentration, the evaluation of a tentative capture framework which combines an oxygen enrichment step before combustion and a CO2 capture step from flue gas has been investigated through a simulation study. The performances of a cryogenic oxygen production process have been used for the upstream part, while a membrane separation process based on CO2 selective materials has been investigated for CO2 capture. The potentialities of this hybrid process from the energy requirement point of view are discussed. It is shown that the hybrid process can lead to a 35% decrease of the energy requirement (expressed in GJ per ton of recovered CO2) compared to oxycombustion, providing optimal operating conditions are chosen.