• Ansys
• CFD
• ciclone
• efficienza
• rimozione delle gocce
• separatore geotermico
• separator efficiency
• cyclone
• droplet removal
• Eulerian Wall Film
• entrainment
• Discrete Phase Model
• Cerro Pabellón
• Geothermal separator
• Fluent
• numerical modeling

The aim of this thesis was to provide an insight into the design of vertical cyclone steam-water separators used to remove droplets from the geothermal fluid extracted from the wells. In particular, the Cerro Pabellón geothermal power plant, in the Atacama Desert in Chile, belonging to Enel Green Power, was taken as a case study.

To this purpose, a numerical model of the turbulent multiphase flow in the separator was developed using Computational Fluid Dynamics. This required a significant understanding and a critical analysis of the sub-models needed to describe the fate of the droplets, including their interaction with the liquid film that develops at the separator walls.

The investigation methodology was based on a gradual increase of the scenario complexity. For instance, a first analysis was performed in dilute conditions (vapor-dominated case) using an Eulerian-Lagrangian approach (Discrete Phase Model - DPM) and the droplet removal efficiency was estimated for different inlet flow rates. Then, dense conditions (liquid-dominated case) have been addressed, these corresponding more to the Cerro Pabellón separators. In such a case the knowledge of inlet droplet size distribution was found to be a critical issue, thus requiring for a further investigation of the incoming flows. Moreover, the implementation of the re-entrainment, due to the presence of the liquid film at the walls (Eulerian Wall Film - EWF), has demanded a better insight into the critical parameters.

Despite the above issues, the present work provided a better understanding of the separator behaviour and gave an indication of the main operating conditions affecting the removal efficiency.