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  • Study location Mälardalen University Campus Västerås, room R2-205/digital
Date
  • 2020-09-09 10:00–12:00

The public defense of Worrada Nookuea's doctoral thesis in Energy and Environmental Engineering

The public defence of Worrada Nookuea's doctoral thesis ”Impacts of thermo-physical properties on the design, operation, and cost of monoethanolamine-based chemical absorption” will take place at Mälardalen University Campus Västerås and digital (Zoom) on September 9.

Title: Impacts of thermo-physical properties on the design, operation, and cost of monoethanolamine-based chemical absorption

Serial number: 317

The examining committee consists of Professor Zaoxiao Zhang, Xi’an Jiaotong University, Associate Professor Matthäus Bäbler, KTH Royal Institute of Technology and Professor Mohsen Assadi, University of Stavanger. Professor Xiaoyan Ji, Luleå University of Technology, as been appointed the faculty examiner..

Reserve is Professor Philip de Vaal, University of Pretoria.


Abstract

The Europe’s energy roadmap to reduced 40% of greenhouse gas emissions by 2030 could only be achieved by implementing carbon capture and storage (CCS) in fossil fuel–based power generations. The thermodynamic and transport properties of CO2 mixtures are essential to the design, operation, and optimization of all CCS processes. To retrieve the accurate property values, the accurate property models are required. However, there are many properties, which are affected by many factors. Moreover, the property model development is behind the requirement of accurate properties. Therefore, it is important to quantify the property impacts on the design of CCS in order to prioritize the development of models of the properties those are the most important ones.

According to the identified knowledge gaps, the impacts of thermo–physical properties, density, viscosity, diffusivity, and surface tension on the column designs for the chemical absorption using aqueous monoethanolamine were selected for quantitative analyses. The in–house rate–based absorption and desorption models were developed in MATLAB to simulate the processes, and the sensitivity study was done for each property.

For the diameter design of absorber and desorber, the gas phase density has the most significant impact. Therefore, for the diameter design, developing more accurate gas phase density models should be prioritised. 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 prioritised. Besides, development of the gas phase diffusivity and density model should be prioritized for the desorber packing height design. 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, for the case of the desorber cost, 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 compared to the desorber. Moreover, the impacts on the concentration profiles are more significant compared with the impacts on the temperature profiles. Regenerating CO2 at elevated pressures shows the potential to reduce the energy penalty of CO2 capture and compression. It was found that the total energy use decreases when the desorption pressure is increased. However, the total exergy increases slightly.