(331h) Optimization of a 4 Step PSA Cycle for CO2 Capture From Post-Combustion Flue Gas

Carbon dioxide capture and concentration from post combustion flue gas is a widely studied contemporary topic. Naturally, the effectiveness of cyclic adsorption processes, such as pressure swing adsorption (PSA), for this important application has been investigated in many recent publications. In these studies, the lower operating pressure varied from 0.5 – 0.005 bar. Similarly, the higher operating pressure varied in the range 1 – 10 bar.

Attaining high purity and recovery (typically 90% and above for both) has the focus of these studies and a variety of cycles differing in number of steps and operations have been used. Energy penalty is another important performance indicator for evaluating a carbon capture process. Consequently, choice of feed pressure and evacuation level are important decisions that affect energy penalty, which have not been critically analyzed.  Moreover, unlike a steady state process, productivity is another performance variable that poses a design challenge. Proper design of a cyclic adsorption process for carbon capture is, therefore, a multi-objective optimization problem that requires finding the operating conditions to minimize energy penalty and maximize productivity while meeting the stringent purity-recovery constraints.

In the proposed talk, we will report the development of a comprehensive non-isothermal, non-isobaric PSA process simulator that is very fast and robust to allow full stochastic optimization without resorting to any model reduction. Using a simple 4-step cycle, 13X zeolite and dry flue gas, the advantages and limitations of pressure swing and vacuum swing cycles will be discussed in detail.