CO₂ absorption and regeneration performance enhancement by nanoabsorbents in combined cycle

다국어 초록 (Multilingual Abstract)

This study attempted to develop new absorbents with enhanced CO2 absorption/regeneration performance by adding nanoparticles to methanol that is used as the absorbent in the Rectisol process, a physical absorption system. The nanoparticles used for the experiments were SiO2 and Al2O3, and their concentration was set as 0.005, 0.01, 0.05, and 0.1 vol%. The dispersion stability of the fabricated nanoabsorbents was evaluated by measuring particle size, turbidity, and zeta potential of the absorbent. The CO2 mass transfer performance of the nanoabsorbents was analyzed by conducting a combined CO2 absorption/regeneration experiment. The experimental results showed that the optimal concentration of the added nanoparticles was 0.01 vol%, and the addition of SiO2 improved CO2 capture by 22%. However, when Al¬2O3 was added, the performance deteriorated. In addition, a literature review was conducted and a high speed camera and related optical techniques were used to analyze the mass transfer enhancement mechanism in nanoabsorbents in order to identify an optimal mechanism. I found that the most effective models for the mass transfer enhancement mechanism were the hydrodynamic effect for the absorption process and the surface effect for the regeneration process.

목차 (Table of Contents)

• Abstract i
• Contents iii
• List of Figures vi
• List of Tables x
• Nomenclature xi
• Chapter I INTRODUCTION 1
• 1.1 CO2 capture 1
• 1.2 Nanoabsorbents 4
• 1.3 Objective of study 6
• Chapter II LITERATURE REVIEW 8
• 2.1 Quiescent absorption 8
• 2.2 Continuous absorption 15
• 2.3 Combined absorption and regeneration 22
• Chapter III EXPERIMENTS 25
• 3.1 Preparation for nanoabsorbents 25
• 3.1.1 Aluminum oxide (Al2O3) 32
• 3.1.2 Silicon dioxide (SiO2) 34
• 3.2 Dispersion stability 36
• 3.2.1 Particle size measurement 36
• 3.2.2 Zeta potential measurement 39
• 3.2.3 Turbidity measurement 42
• 3.3 Bubble absorption experiment 44
• 3.4 Visualization experiment 47
• 3.5 Combined absorption and regeneration experiment 51
• Chapter IV RESULTS AND DISCUSSION 61
• 4.1 Dispersion stability 61
• 4.1.1 Cluster particle size 61
• 4.1.2 Zeta-potential 66
• 4.1.3 Turbidity 68
• 4.2 Bubble absorption 71
• 4.3 Absorption visualization 77
• 4.3.1 Single CO2 bubble 77
• 4.3.2 CO2 diffusion 80
• 4.4 Enhancing factors of nanoabsorbent effect 83
• 4.4.1 Critical concentration 84
• 4.4.2 Particle size 89
• 4.4.3 Particle species 91
• 4.4.4 Thermal conditions 92
• 4.4.5 Gas-liquid contactor type 97
• 4.5 Mass transfer enhancement mechanisms 98
• 4.5.1 Absorption enhancement mechanisms 98
• 4.5.2 Regeneration enhancement mechanisms 104
• 4.6 Combined absorption and regeneration 108
• 4.6.1 Absorbent 108
• 4.6.2 Regeneration 112
• Chapter V CONCLUSIONS 122
• Appendix A. ENERGY SAVING BY NANOABSORBENTS 124
• REFERENCES 131