Mixing and Separating - from Detail to Apparatus
The separation of liquid/liquid mixtures in gravity separators is a widely used and mandatory standard operation in process engineering.
It is used whenever two-phase mixtures of organic and aqueous liquids have to be separated, e.g.: Hydrocarbons/water in petroleum processing; Solvents/water in the production of plastics, paints, rubbers, pesticides, vitamins, foodstuffs and their intermediate and co-products; Methyl ester/glycerine in biofuel production. Typically, vessels with a diameter of 0.5 - 5 m and a length of 3 - 30 m are used for the separators. Depending on the material and pressure rating, container costs of approx. €20,000 to €1,000,000 can be expected.
The aim of the project is to develop a practical standard by means of flow simulation (computational fluid dynamics, CFD for short) in order to calculate the flow pattern - and thus the partial residence time distribution - in any separator on the basis of available process data.
The additional implementation of the droplet behaviour. (coalescence, phase boundaries) will also enable the calculation of the separator efficiency. For this purpose, a numerical framework will be created that allows the phase boundary to be described unambiguously, but also the disperse particle size distribution to be resolved using a combined class and moment method. The knitted fabrics used are characterized in more detail by means of tomography, and the model approaches are extended or newly developed on the basis of detailed investigations of wetting and deposition.
Finally, the simulation methodology is compared with pilot scale experiments.