Analysis of combined process flow sheet modifications for energy efficient CO2 capture from flue gases using chemical absorption

AbstractThe energy penalty associated with solvent absorption based Post Combustion CO2 Capture is one of the main stumbling blocks for the implementation of this technology into new and existing fossil-fired power stations. Modifying the flow sheet of the standard chemical absorption process can allow for reductions in the energy and resource usage of such plants. A review of the open and patented literature highlighted modifications, predominantly related to applications in the gas processing industry. These modifications were modelled using commercially available rate based simulation software. This allowed the expected energy consumption of a CO2 capture pilot plant, based in Australia, to be estimated. The modelling results pointed towards the optimal conditions for each modification. Selected modifications were then added together to determine whether any synergistic effects could be observed. The split flow process was found to have one of the highest energy savings (reduction in reboiler duty) over the reference plant. Adding inter-cooling on the absorber column with splitting of the rich solvent stream entering the stripping column showed a reduction in reboiler duty slightly greater than anticipated based on the results of the individual modifications