A novel process for cryogenic CO2 capture using dynamically operated packed beds—An experimental and numerical study

A novel process concept has been studied for post-combustion CO2 capture from flue gases based on periodic operation of cryogenically cooled packed beds. Using refrigerated packed beds, an effective separation between H2O, CO2 and the permanent gases can be obtained at atmospheric pressures, due to differences in dew and sublimation points. H2O and CO2 will respectively condensate and desublimate onto the packing surface at different locations, while the permanent gases will pass through the bed. In this work the evolution of the axial temperature and concentration profiles during the consecutive capture, recovery and cooling cycles has been investigated in detail by experiments and numerical simulations, elucidating the effect of the initial bed temperature and feed CO2 and H2O concentrations. Furthermore, the required cooling duties were calculated for different CO2 concentrations in the flue gas and initial bed temperatures. The required cold duty to recover >99% CO2 from a flue gas containing 10 vol.% CO2 and 1 vol. H2O is estimated at 1.8 MJ/kgCO21.8 MJ/kgCO2, where lower CO2 concentrations in the inlet and higher initial bed temperatures result in higher required cooling duties per mass of CO2 captured.