Efficient selection of conventional and phase-change CO2 capture solvents and mixtures based on process economic and operating criteria

Abstract

The aim of this work is to exploit shortcut models in order to efficiently assess conventional and phase-change solvents and mixtures based on CO2 capture and upstream plant process and economic performance criteria. This is approached by exploiting a previously available shortcut model which is currently suitable only for solvents exhibiting vapor-liquid equilibrium (VLE) behavior. This model is extended to account for solvents which exhibit vapor-liquid-liquid equilibrium (VLLE), phase-change behavior and is implemented in 10 solvents and mixtures, including 2 phase-change solvents. The VLE behavior of conventional solvents and mixtures is represented using models obtained from literature or regressed from experimental data. The VLLE behavior of the phase-change solvents MAPA/DEEA (3-(methylamino)propylamine/2-(diethylamino)ethanol) and MCA (methyl-cyclohexylamine) is modelled through regression curves from experimental data. The performance criteria for solvent assessment include cyclic capacity, solvent flowrate and purchase cost, regeneration duty, net efficiency penalty and lost revenue of power plant from parasitic electricity due to capture. The performance of the phase-change solvents is validated based on literature data, whereas it is superior to that of conventional CO2 capture solvents. The net efficiency penalties of MCA and MAPA/DEEA are approximately between 2.9 and 3.3% points lower than MEA (monoethanolamine), whereas the lost revenue of the power plant due to the capture unit is 47% and 50% lower than MEA, respectively.