CO₂ Capture from Flue Gas by Vacuum Swing Adsorption

CO2 CAPTURE FROM FLUE GAS BY VACUUM SWING ADSORPTION
Augustine Ntiamoah, Paul Webley, Penny Xiao

Vacuum swing adsorption is a promising low energy technology for recovering CO₂ from low pressure flue gas streams. In this process, the flue gas is contacted with the adsorbent at atmospheric pressure and the carbon dioxide adsorbs onto the adsorbent in the bed. The adsorbent bed is then reduced in pressure to remove and recover the adsorbed carbon dioxide. Since carbon dioxide is adsorbed much stronger than nitrogen, it is possible to obtain a stream of enriched carbon dioxide. Unfortunately, the purity of carbon dioxide achieved is still not sufficient for sequestration unless very low vacuum levels are used. To overcome this problem, we have developed novel vacuum swing adsorption cycles in which additional pressure equalisation and heavy product reflux steps have been added. This allows us to achieve high purity product without applying excessive vacuum levels.