Hybrid Adsorption-Liquefaction Process for Post-combustion CO 2 Capture

The potential of a hybrid process combining two separation processes: pressurevacuum swing adsorption (PVSA) and cryogenic CO 2 purification/liquefaction is explored using a system-level integrated techno-economic optimization framework. Detailed process models of the PVSA and the liquefaction units developed in gProms were used to train Artificial Neural Network (ANN) based surrogates. These surrogates were integrated with a detailed costing framework to perform techno-economic optimization of both standalone PVSA and hybrid processes. A wide range of flue gas CO 2 compositions ranging from 3.5-30 mol % are studied. Unconstrained cost optimizations of a standalone PVSA process for feed CO 2 compositions ≤13 mol% showed that at low-purity levels (≤60 mol%) and high recovery levels (≥90%), the cost of CO 2 avoided reduced by more than half compared to when the standalone-PVSA process produces both high purity (≥95 mol%) and high recovery (≥90%). Parametric analysis of a cryogenic CO 2 purification process showed that a high level of purification (purity ≥ 98 mol%) is achievable with only two flash stages, with reasonable recoveries. The hybrid process was found to be cost-competitive with a conventional monoethanolamine (MEA) absorption process for flue gas CO 2 compositions ≥7.5 mol% under the constraints of ≥95 mol% purity and ≥90% overall recovery. The key advantages of the hybrid are the avoidance of deep vacuums, the reduction in plant footprint, and the ability to meet product oxygen specifications.