(21a) 13X Zeolite Modification for Process Scaling and Design of Large Scale PSA CO2 Capture

The flowrate of flue gas produced from a 550 MW coal-fired power plant is extremely large and can exceed 25,000,000 SLPM. According to the Department of Energy (DOE), the goal is to capture and concentrate the CO₂ from flue gas and produce it in a stream containing at least 95 vol% CO₂ with at least 90 % recovery and with less than 10 ppm of O₂. Pressure and vacuum swing adsorption (PVSA) processes using commercial 13X zeolite beads are being touted for this application. One of the main issues with low pressure flue gas streams is the axial pressure drop. The pressure drop during the feed step is limited to 15kPa with the exit pressure at 101.3 kPa; otherwise, the cost of compression is too high. Moreover, the regeneration steps typically consisting of countercurrent depressurization (CnD) and light reflux (LR) steps also have a limit on the magnitude of the axial pressure drop. If it is too large then the beds won’t be effectively regenerated. These axial pressure drops limit the bed configuration and thus limits the minimum total number of beds required in the VSA system. In this work, adsorbent modifications are investigated with a unique scaling procedure to meet these constraints while minimizing the total number of beds required in the VSA system. These are accomplished by changing the adsorbent size and tuning the adsorption isotherms. These scaling analyses were validated by rigorous dynamic adsorption process simulator (DAPS) and the results showed that the modification of 13X zeolite can reduce the total number of beds significantly.