Filtration of Liquid Aerosols

International audienceLiquid aerosols can make up a considerable portion of atmospheric pollution in mechanical industries (mists generated by oil application in the machining of metals or the production of compressed gas) and agricultural industries (phytosanitary products), among others. These liquid aerosols, in the form of oil mists, are mainly produced by three different processes:– Mechanical atomization: Many authors demonstrate that at very high rotational velocities (therefore with a very high shearing force), the liquid that comes into contact with the rotatory equipment acquires sufficient mechanical energy to disaggregate into small droplets.– Evaporation–condensation: Several authors report that due to the extreme temperatures present during machining, one part of the liquid evaporates and subsequently condenses to form droplets, in a slightly cooler region, around liquid nuclei that form spontaneously or onto foreign particles.– Entrainment by gas flow in gas–liquid contactors: Schaber et al. estimate that gas moving through cooling towers, from plate columns, etc., can carry along liquid droplets. Measurements at the output of the condensors and absorbers typically give values of the order of 105–107 droplets per cubic centimeter, and the diameter of the droplets ranges from 0.5 to 3 μm