Impacts of Thermo–Physical Properties on the Design, Operation, and Cost of Monoethanolamine–Based Chemical Absorption

Sammanfattning: The thermodynamic and transport properties of CO2 mixtures are essential to the design, operation, and optimization of all carbon capture and storage processes. To retrieve accurate property values, accurate property models are required. However, there are many properties, which are in turn affected by many factors. Moreover, property model development is behind the requirement of accurate properties. Therefore, it is important to quantify the property impacts on the process design for CCS to prioritize the development of models of the properties that are the most important ones.According to the identified knowledge gaps, the impacts of the following thermo-physical properties were selected for quantitative analysis: density, viscosity, diffusivity, and surface tension on the column designs for the chemical absorption using aqueous monoethanolamine. The in–house rate–based absorption and desorption models were developed in MATLAB to simulate the processes, and sensitivity studies were done for each property. For the diameter design, developing more accurate gas phase density models should be prioritized. However, developing a more accurate liquid phase density model is also important, due to its significant impact and larger model uncertainty range. For the absorber packing height design, development of the liquid phase density and viscosity models should be prioritized. In addition, for the desorber packing height design, development of the gas phase diffusivity and density model should be prioritized. Regarding the impacts on the cost of the absorber and the overall equipment, development of the density and viscosity models of the aqueous amine solution with CO2 loading should be prioritized. However, as far as desorber cost is concerned, development of the gas phase density and diffusivity model of the CO2/H2O mixture should be prioritized.The rate-based chemical absorption and desorption models were developed in Aspen Plus to evaluate the impacts of mass transfer coefficient models and desorber pressure. The liquid mass transfer coefficient has more significant impacts on the simulation of the absorber than it does to the simulation of the desorber. Moreover, the impacts on the concentration profiles are more significant compared to those on the temperature profiles. In addition, regenerating CO2 at elevated pressures shows the potential to reduce the energy penalty of CO2 capture and compression.