Process modifications for solvent-based post-combustion CO₂ capture

One of the major limitations to the implementation of amine based post-combustion CO₂ capture (PCC) technology is the high efficiency loss induced by the process. Minimizing this loss can be achieved by either formulating new solvents and/or optimizing the process flow-sheet and/or its integration with the power plant. Amine based CO₂ scrubbing processes have been patented since 1930 but very few process improvements have been reported prior to the oil crisis of 1975–1980, which led to the requirement for more energy efficient processes. Nevertheless most of these patents are solvent oriented. With CO₂ capture technology development, a sharp increase of process improvement patents and scientific articles can be witnessed since 2004 in parallel with the development of new solvents.

In this work, a thorough review of patent database and open literature has been carried out in order to be as exhaustive as possible. The individual process modifications are analyzed and then generalized into “elementary” modification groups. These 20 elementary modifications are then sorted out in 3 main categories related to their effect on the process: linked to absorption enhancement, heat integration and heat pump. Absorption enhancement includes 6 modifications: intercooled absorber (ICA), rich solvent recycle (RSR), interheated absorber (IHA), split flow arrangement (SFA), double loop absorber (DLA), flue gas compression and expansion (FCE). Heat integration includes 9 modifications: rich solvent splitting (RSP), rich solvent preheating (RSP), rich solvent flashing (RSF), parallel economizer arrangement (PEA), interheated stripper (IHS), heat integrated stripper (HIS), overhead condenser bypass (OCB), vacuum operated stripper (VOC), multi-effect stripper (MES). Heat pump includes 5 modifications: lean vapor compression (LVC), rich vapor compression (RVC), integrated heat pump (IHP), stripper overhead compression (SOC), multi-pressure stripper (MPS).