Design and verification of a Hydraulic Air Compressor as a CO2 capture and sequestration system.

Abstract

As a result of human activities, the level of atmospheric carbon dioxide (CO2) has increased. Carbon capture and sequestration (CCS) technologies offer an effective approach for mitigating CO2 from various industrial process to reduce the global climate change effect. These technologies can be integrated into existing infrastructure with minimal disruption. This study reviews on post- combustion CO2 capture and sequestration techniques, with a specific focus on mineral carbonation process routes and their potential feedstocks. Mineral carbonation is an approach that mimics the natural weathering of rock, in which metal oxide-bearing materials, for instance natural silicate minerals (serpentinite, olivine) react with gaseous CO2 to form solid carbonates. This process takes place on geological time scales, but it can be accelerated by increasing the concentration of CO2 in a reactor through pressurization of the system. The purpose of this study was investigation of technical feasibility of a CCS process by means of a hydraulic air compressor (HAC). A series of experiments were conducted on the HAC pilot plant to investigate the potential of the system as a post-combustion CO2 capture system. Those experiences experimentally verified a one-dimensional steady-state model for two-phase bubbly flow. The verified bubbly flow model was used to compare the hydrodynamics and mass transfer characteristics of HAC downcomers and upward co-current flow bubble column reactors and to predict gas liquid mass transfer coefficients. The experimental results showed that the HAC is an effective technology for intensification of CCS processes due to its improved mass transfer performance compared to other mass transfer devices. While the high capital cost of HAC construction, following a general Millar (2014) design paradigm, limits applicability, the horizontal injector loop (HIL), developed in this thesis offers a new apparatus with similar gas compressor performance and reduced height, which would make the concept more accessible for capital restricted projects. A mathematical dynamic kinetic model is developed to simulate the kinetics of CO2 absorption into an alkaline solution in the HIL. This model makes a significant contribution in predicting the absorption rate under operating conditions beyond those achievable in experimental tests undertaken. In addition, this model can be used to guide the design of a new reactor and future experiments, making it a valuable tool for CO2 capture and sequestration activity. Carbon dioxide capture and sequestration by means of a HIL as a pressurized, continuous chemical reactor was also investigated experimentally. The experimental results demonstrated that the HIL has a credible potential for this purpose. These experiments were also simulated using the dynamic kinetic model, which showed good agreement with the experimental findings. However, some potential improvements to the dynamic kinetic model have been identified to enhance its compatibility with experimental conditions.