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Following the climate change mitigation target in Paris agreement, the global warming has to be limited to 2.0°C above the preindustrial levels. One of the potential methods is carbon capture and storage (CCS), which can significantly reduce the CO₂ emissions from the vast point sources such as power plants, industries, and natural gas processes. The CCS covers four steps which are capture, conditioning, transport, and storage. For the capture part, post-combustion capture is easier to implement based on today’s technologies and infrastructure compared with pre-combustion and oxy-fuel combustion captures, since the radical changes in the structure of the existing plant are not required.

To design and operate different CCS processes, the knowledge of thermo-physical properties of the CO₂ mixtures is of importance. In this thesis, the status and progress of the studies related to the impacts of the uncertainty in thermo-physical properties on the design and operation of the CCS processes were reviewed. The knowledge gaps and the priority of property model development were identified.

According to the identified knowledge gaps in the review, the impacts of thermo-physical properties which are the density, viscosity, and diffusivity of the gas and liquid phases, and the surface tension and heat capacity of the liquid phase on the design of the absorber column for the chemical absorption using aqueous monoethanolamine were quantitatively analyzed. An in-house rate-based absorption model was developed in MATLAB to simulate the absorption process, and the sensitivity study was done for each property. An economic evaluation was also performed to further estimate the impacts of the properties on the capital cost of the absorption unit. 

For column diameter of the absorber, the gas phase density shows the most significant impacts; while, the liquid phase density and viscosity show the most significant impacts on the design of the packing height and also the capital cost of the absorption unit. Therefore, developing the flue gas density model and liquid phase density and viscosity models of the aqueous solvents with CO₂ loading should be prioritized.

Enligt Parisavtalets mål för klimatförändringar ska den globala uppvärmningen begränsas till 2.0° C över förindustriella nivåer. En av de potentiella metoderna är avskiljning och lagring av koldioxid (CCS), som avsevärt kan minska CO₂-utsläppen från stora punktkällor såsom kraftverk, industrier och naturgasprocesser. CCS omfattar fyra steg som är avskiljning, konditionering, transport och lagring. Avskiljning genom efterförbränning är lättare att genomföra baserat på dagens teknik och infrastruktur jämfört med avskiljning före förbränning och genom oxybränsle förbränning, eftersom radikala förändringar av de befintliga anläggningars struktur inte behövs.

För att utforma och driva olika CCS processer, är kunskap om termofysikaliska egenskaperna hos CO₂ blandningarna av stor betydelse. I denna avhandling har status och framsteg för studier rörande effekterna av osäkerheten i termofysikaliska egenskaper på konstruktion och drift av CCS processer granskats. Kunskapsluckor och prioritering av utveckling av modeller för egenskaperna identifierades.

Enligt de i översynen identifierade kunskapsluckorna, har effekterna av de termofysikaliska egenskaperna densitet, viskositet och diffusivitet av gas- och vätskefaserna, och ytspänningen och värmekapacitet av vätskefasen på utformningen av absorptionskolonnen för kemisk absorption med användning av vattenhaltig monoetanolamin analyserats kvantitativt. En hastighetsbaserad absorptionsmodell har utvecklats i MATLAB för simulering av absorptionsprocessen och känslighetsanalys gjordes för varje egenskap. En ekonomisk utvärdering genomfördes också för att ytterligare uppskatta effekterna av egenskaperna på kapitalkostnaden för absorptionsenheten.

För bestämning av diametern av absorbatorns kolonn visar gasfasens densitet den mest betydande inverkan; medan vätskefasens densitet och viskositeten visar den mest betydande inverkan på utformningen av fyllmaterialets höjd och även kapitalkostnaderna för absorptionsenheten. Därför bör utveckling av modeller för rökgasens densitet och vätskefasens densitet och viskositet för det vattenbaserade lösningsmedlet med absorberad CO₂ prioriteras.

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.