Screening of flowsheet modifications for an efficient monoethanolamine (MEA) based post-combustion CO2 capture

Abstract

The purpose of this study is to assess and compare most of the CO2 capture unit flowsheet modifications described in the literature through modelling. The main component of the process, absorber and stripper were specifically modelled around a rate based model with mass transfer and chemical kinetics. The solvent used for the study is monoethanolamine (MEA). The different case studies are compared to a reference case presenting a standard good performance in term of energy consumption (3.7 GJ/tCO2 at 1atm). Their impact on the thermal power plant is also briefly studied in order to permit the performances comparison in term of plant efficiency (electric power output/coal lower heating value).The best individual simple modifications are: a stripper operating with moderate vaccum pressure (around 0.75bar), the staged feed of the stripper, the lean solvent vapour compression, the overhead stripper compression. They allow a decrease of efficiency penalty by 4–8%. Some other modifications contribute to the good performance of the process such as: intercooler, improved economizer, boiler condensate vapour compression, with a reduction of efficiency penalty around 2%. These individual modifications can be combined in order to build very efficient process with efficiency penalties reduction ranging from 10% to 25%. Finally, some drastic process modifications can improve very significantly the process performance such as: advanced split-flow with a reduction of efficiency penalty by around 30% or direct steam stripping with a reduction of efficiency penalty of 27%.A qualitative summary of one to one interaction between process modifications is proposed. These process modifications must be coupled with new solvents and innovative power plant heat integration strategies in order to show the true potential of the amine-based post-combustion capture processes.