Investigation of the separation behaviour of oil mist filters under real conditions on screw compressors
Various industrial processes generate aerosols containing fine oil droplets. An example of such a process is the generation of compressed air by oil-lubricated screw compressors. Screw compressors are operated mostly oil-lubricated. Lubrication is needed to cool and lubricate the rotors as well as to seal the volume of the chambers between the screws. As the screws rotate, the oil is dispersed into fine submicron droplets due to the present shear forces. These oil droplets in the compressed air (oil mist) are typically separated with the aid of coalescence separators. The required purity downstream of the separator is dependent on the applicable pollution limits (e.g. in terms of health and safety regulations). The classification of the purity is often based on ISO 8573. To design a coalescence separator precise knowledge of the operating behavior is required.
In practice, the selection of suitable coalescence filter media is made mainly empirically on the basis of experience in different applications. The influence of operating conditions and media parameters on the temporal development of differential pressure and separation efficiency of the coalescence filter has been insufficiently investigated. Within the scope of this work, the relationship between operating and structural parameters of coalescence separators and their influence on the operating and separation behavior is studied. The aim of this work is to use the findings to develop a practical evaluation and design methodology for specifications and quality assurance of coalescence separators.