Design guidance for an energy-thrift absorption process for carbon capture: Analysis of thermal energy consumption for a conventional process configuration

• Solvent development guidance is provided for the absorption-based process.
• Factors affecting thermal energy demand are analyzed quantitatively.
• Minimum achievable thermal energy is estimated to be 2.3–2.5 GJ/t-CO2.

The development of an energy-thrift carbon capture process to reduce atmosphere CO2 emissions is an urgent need; however, comprehensive and systematic design guidelines for energy-minimized gas separation processes are not easily available. This study aims to understand the fundamentals of thermal energy usage in an absorption system and provide quantitative and integrated guidelines to design a minimum-energy-demanding, absorption-based carbon capture process using aqueous solvents. Solvent capacity and absorption performance are the most important factors, whereas the heat of reaction, considered important in many studies, is actually not a critical factor to determine the thermal energy usage. The shape of the vapor–liquid equilibrium curve also has a significant effect on the regeneration energy. When designing a minimum thermal energy process, the cyclic capacity, absorption performance, and heat of reaction should be considered simultaneously rather than separately because they affect the total thermal energy demand interactively. The minimum achievable regeneration energy in an absorption-based process with a typical process configuration for coal-fired plant flue gas was estimated as 2.3–2.5 GJ/t-CO2 with an optimized heat of reaction of approximately 60–70 kJ/mol-CO2. Brief analysis of the equivalent work up to the compression stage was also made, and the relationship with the thermal energy is discussed. The fundamentals learned through this study can be extended to other absorption-based gas separation processes.

Quantitative and integrated guidelines are provided to design a minimum-energy-demanding carbon capture process using aqueous solvents.Figure optionsDownload as PowerPoint slide