The removal of fine particles from gases can be considerably simplified if the particles are first enlarged into greater ones by a preconditioning technique. Such preconditioning can be the heterogeneous condensation of water vapor with the fine particles acting as nucleation centres [1,7], for which a supersaturated water vapor environment is required. When the degree of supersaturation exceeds a critical value Scr, the particles can be activated and grow into larger droplets that can be efficiently removed by conventional
separators.