(47g) Density of CO2 Loaded Carbon Capture Water Lean Solvents – Measurement and Modeling

Water lean solvents have recently demonstrated strong advantages for carbon capture compared to traditional aqueous solvents. Robust and accurate process simulation models of the interactions of the solvent and carbon dioxide are critical for equipment sizing, evaluation of different process configurations and operating conditions of carbon capture processes. Obtaining accurate measurements of all the properties at all the relevant conditions of interest for model development is prohibitively time consuming and expensive; as such, a strategy was developed for a pragmatic fluid characterization process. Fluid density is a thermophysical property with significant importance in the process simulation of carbon capture systems and therefore a compelling example to illustrate the fluid characterization process.

The lean and rich solvent density was measured for a water lean solvent with an Anton Paar DMA HPM densitometer over a wide temperature range and carbon dioxide loadings. A novel method was used to prepare the solvent mixtures and the loaded solutions to reduce the uncertainties in the compositions of the fluids being measured. As the solvent is a multicomponent liquid system, the pure and binary mixtures of the constituents of the water lean solvent were also measured to help understand the mixing behavior of the system and to aid in the model development. The individual components of the water lean solvent have limited solubilities in each other, and special attention was made to determine the phase boundaries of the mixtures.

The experimental densities of the pure components, binary mixtures and CO₂ loaded and unloaded solvents were correlated as functions of temperature and composition. The new experimental and model results will not only be useful to evaluate the volumetric properties in water lean solvents systems, but also provide a solid foundation for nearly all properties and process simulation models at relevant operating conditions.