New pressure swing adsorption cycles for carbon dioxide sequestration
A rigorous pressure swing adsorption (PSA) process simulator was used to study a new, high temperature PSA cycle, based on the use of a K-promoted HTlc adsorbent and a simple, 4-step, Skarstrom-type, vacuum swing cycle designed to process a typical stack gas effluent at 575 K containing (in vol%) 15% CO2, 75% N2 and 10% H2O. The effects of the purge-to-feed ratio (?), cycle step time (ts) (with all four steps of equal time), and pressure ratio (? T) on the process performance was studied in terms of the CO2 recovery (R) and enrichment (E) at a constant throughput ? of 14.4 L STP/hr/ kg. R increased with increasing ? and ?T and decreasing ts, while E increased with increasing ts and ? T and decreasing ?. The highest E of 3.9 was obtained at R = 87% and ?T = 12, whereas at R = 100% the highest E of 2.6 was obtained at ?T = 12. These results are very encouraging and show the potential of a high temperature PSA cycle for CO2 capture.