Droplet formation and reduction in thermal separation devices
Subproject: Experimental analysis of the two-phase flow with phase transition in feed pipes
Many thermal separation processes are operated with counter-current vapor-liquid flow. The efficient separation driven by thermodynamic non-equilibrium between gas and liquid phase is achieved by high turbulence as well as large interfacial area. At the same time, intensive interactions between vapor and liquid phases result in the formation of droplets at specific positions in separation columns (feeding and drawing points at feed inlet, head and sump of columns and reboilers), which requires auxiliary equipments for the droplet separation.
Droplets entrained by the vapor phase may drastically reduce the separation capacity of columns and affect the energy efficiency of the process. Furthermore, droplet carry-over into the downstream process units may cause severe corrosion problems, process instabilities as well as higher emissions and may eventually result in process shutdowns.
Within the joint project ‘TERESA’, improved design tools for phase and droplet separation equipment will be developed and new concepts for separation equipments will be proposed.
Core of the investigations at HZDR are the flow characterization in feed pipes (200 mm inner diameter and length of approx. 4 m) with flash evaporation. For this purpose, experimental studies are performed in a column (500 mm inner diameter and height of approx. 5 m) operated with a refrigerant fluid featuring industry relevant physical properties such as surface tensions, which significantly influence the evolving droplet size spectra. Besides, extensive characterization of the two-phase flow of the feed pipe at transient conditions via wire-mesh sensors will be performed, and various phase and droplet separator internals will be tested to evaluate their separation efficiency.
- TU Braunschweig,
- Ruhr-Universität Bochum,
- TU Kaiserslautern,
- DencoHappel GmbH,
- ENVIMAC Engineering GmbH,
- Falk & Thomas Engineering GmbH,
- horst weyer und partner GmbH,
- HZDR Innovation GmbH,
- Linde AG,
- Munters Euroform GmbH,
- Raschig GmbH,
- RVT Process Equipment GmbH
Bundesministerium für Wirtschaft und Energie (BMWi, 03ET1395)
- C. Vallée, T. Höhne, H.-M. Prasser, T. Sühnel
Experimental investigation and CFD simulation of horizontal stratified two-phase flow phenomena
Nuclear Engineering and Design 238, 3, 637-646 (2008)