Cascaded Membrane Processes for Post‐Combustion CO2 Capture

CO2 fugacity difference is the driving force for CO2‐selective membranes used in post‐combustion capture. The ambient pressure of the flue gas makes it very difficult to use only a single membrane stage to achieve the CO2 purity required by pipeline transport and storage, e.g., 95 mol.‐%. On the basis of a general multi‐stage membrane concept, an energy‐efficient membrane cascade is developed. The correlation of energy consumption and membrane area of a cascaded membrane process is investigated, considering 50 %, 70 %, and 90 % degree of CO2 separation. In addition to an idealized flue gas consisting of N2 and CO2 only, also a quasi‐real flue gas is studied. Pressure loss in membrane modules and their influence on process energy consumption are discussed.