Process Integration of Post-combustion CO₂ Capture with Li₄SiO₄/Li₂CO₃ Looping in a NGCC Plant

Lithium-based sorbents require lower energy requirements for regeneration than other more studied and well known materials such as those used in the calcium looping process; however, thermodynamic assessments of these sorbents in power plants are currently missing. Accordingly, in this work, a thermal integration study of a post-combustion CO₂ capture plant using regenerable lithium-based high temperature solid sorbents into a natural gas combined cycle (NGCC) plant has been conducted. A process simulation study has been completed for integration of a Li₄SiO₄/Li₂CO₃ looping cycle downstream of the gas turbine in a NGCC plant. A comparison between this technology and a chemical absorption capture plant with two different solvents, namely conventional monoethanolamine (MEA) and a second generation solvent (CESAR-1), has been established based on the European Benchmarking Taskforce (EBTF) methodology. The integration of post-combustion CO₂ capture in the power plant results in a decrease of its net electric efficiency. However, capture with Li₄SiO₄ sorbents decreases the efficiency by 6.9 percentage points, which is lower than the 8.4 and 7.5 percentage points decrease obtained when CO₂ capture is based on chemical absorption with MEA and CESAR-1 solvents, respectively. Hence, Li₄SiO₄/Li₂CO₃ looping is a promising alternative to amine-based systems when integrated into NGCC plants. Furthermore, additional improvements could be achieved through improved capture process heat integration and optimization. Published by Elsevier Ltd.