Large-scale optimization strategies for pressure swing adsorption cycle synthesis

Pressure swing adsorption (PSA) is an efficient method for gas separation and is a potential candidate for carbon dioxide (CO2) capture from power plants. However, few PSA cycles have been designed for this purpose; the optimal design and operation of PSA cycles for CO2 capture, as well as other systems, remains a very challenging task. In this study, we present a systematic optimization-based formulation for the synthesis and design of novel PSA cycles for CO2 capture in IGCC power plants, which can simultaneously produce hydrogen (H2) and CO2 at high purity and high recovery. Here, we apply a superstructure-based approach to simultaneously determine optimal cycle configurations and design parameters for PSA units. This approach combines automatic differentiation, efficient ODE solvers for the state and sensitivity equations of the PSA model, and state of the art nonlinear programming solvers. Three optimization models are proposed, and two PSA case studies are considered. The first case study considers a binary separation of H2 and CO2 at high purity, where specific energy is minimized, whereas the second case study considers a larger five component separation. (C) 2012 American Institute of Chemical Engineers AIChE J, 2012