Multi-Objective optimization of a selexol® process for the selective removal of CO2 and H2S from coal-derived syngas

This paper focuses on the multi-objective optimization of a Selexol® process for the selective removal of CO2 and H2S from coal gasification-derived syngas. A systematic analysis based on a thorough literature review of scheme options, detailed process simulation (including also a properly calibrated PC-SAFT Equation Of State) and design optimization is carried out. More in detail, the design optimization procedure enables the simultaneous optimization of process, utility design, and heat integration, and takes account all of the interactions with the rest of the plant. The multi-objective optimization is carried out with a two-stage approach combining the NSGA-II genetic algorithm with the efficient direct-search method PGS-COM. Results show that in the Selexol® process is crucial to optimize the pressures of the flash cascade releasing the CO2-rich stream to store, because the largest energy penalties are the compression power and the steam necessary for reboiling.