Post-combustion carbon capture for tank to propeller via process modeling and simulation

Abstract The International Maritime Organization (IMO) has issued a long-term sustainable strategy to gradually phase out the major ship-related sources of greenhouse gas emissions. While the post-combustion carbon capture has been well investigated for onshore plants, the maritime carbon capture system is still in an early stage due to its unique characteristics and design limitations. Aiming at providing a holistic way to find the most efficient and sustainable PCC solution for an LNG tanker, this work proposed a system of the tank to propeller post-combustion carbon capture which integrates ship engine process modeling with chemical absorption/desorption process modeling techniques. A rate-based aqueous monoethanolamine (MEA) process model was developed and validated, then scaled up and modified to capture CO2 from the flue gas. To increase the carbon capture efficiency and decrease the energy penalty, this work provided detailed steps for process model development covering innovative absorber/stripper design under variation of solvents, packed type, and liquid to gas ratio. This work also included a thorough sustainability evaluation based on emission reduction efficiency, energy penalty, and carbon cyclic capacity among two single aqueous amines, MEA and diisopropanolamine (DIPA), and one blended amine with a promoter, methyldiethanolamine (MDEA) with piperazine (PZ). Although DIPA presented a better performance on energy requirement for solvent regeneration, the blended amine was the optimal solvent to meet the requirement of the IMO carbon abatement strategy. Compared to the seven molality MEA, the MDEA-PZ option could capture more than 57 % CO2 while around 25 % specific reboiler duty can be saved.