(338o) Influence of the PSA Cycle Schedule On Carbon Dioxide Capture From Flue Gas

Ritter, J. A., University of South Carolina
Ebner, A. D., University of South Carolina
Mehrotra, A., University of South Carolina

With the simple graphical approach for complex pressure swing adsorption (PSA) cycle scheduling that the authors developed recently, new multi-bed PSA cycle schedules have been devised and are being explored for CO2 capture from flue gas. This new methodology involves a priori specifying the cycle steps, their sequence, and the number of beds, and then following a systematic procedure that requires filling in a 2-D grid based on a few simple rules, some heuristics and some experience. The outcome or solution is a grid comprised of columns that represent the total cycle time, rows that represent the total number of beds, and cells that represent the duration of each cycle step, i.e., the complete cycle schedule.

This PSA cycle schedule analysis has revealed that the design of a multi-bed PSA process for CO2 capture from flue gas is a non-trivial exercise. Since the PSA beds are always coupled together, usually contain more than one layer of adsorbent, and operate sequentially with each undergoing cycle steps such as pressurization, feed, heavy reflux, equalization, depressurization, light reflux, and repressurization, the number of possible cycles to explore becomes enormous, and unfortunately design strategies on how to best configure such a complex PSA cycle is more of an art than a science. To this end, this presentation will show how sensitive the performance of a PSA process is to slight changes in the PSA cycle schedule. It will also show that a PSA process can be easily designed to capture CO2 from flue gas with greater than 90% purity and 90% recovery, even in the presence of water vapor. Thus, this presentation will also demonstrate the applicability of PSA for CO2 capture from flue gas.