Ammonia as an Absorbent of Carbon Dioxide in Post-Combustion Capture - an Experimental, Technical and Economic Process Evaluation

Carbon capture and storage is vital to facilitating the transition from our current fossil fuel-based energy system to a sustainable energy system. The concept of post-combustion capture is based on the selective chemical absorption of carbon dioxide (CO2). The highly concentrated CO2 stream that is suitable for storage is generated by heat-induced regeneration of the solvent. In this work, ammonia is evaluated as an absorbent of CO2 in post-combustion capture processes. The major goals of this thesis are to define favorable applications and local conditions for ammonia-based post-combustion capture processes. The current benchmarking absorbent, monoethanolamine (MEA), has inherent problems is associated with specific drawbacks, such as a high heat requirement for regeneration and a tendency to undergo degradation during operation. Several novel absorbents, including ammonia, have been proposed as being superior to MEA in these aspects. The major disadvantage of ammonia is its volatility, which results in loss of absorbent (slip).This thesis reveals the results of experimental, technical and economic performance analyses. To evaluate the capture process, validation of thermodynamic models of the NH3-CO2-H2O system is required. These thermodynamic models rely on a comprehensive experimental data on the solid-liquid-gas equilibrium for all operating conditions. This work presents new gas-liquid equilibrium data for temperatures that are relevant to the absorber