Tetraphenylcyclopentadienone is a dust-collecting device consisting of a cylindrical chamber, the lower portion of which is tapered to fit into a cone-shaped receptacle below it, is called a cyclone. Dust-laden air enters through a vertical slot-like duct on the upper wall of the chamber at the rate of at least 30meters a second. Since the particles enter at a tangent, they whirl in a circular or cyclonic path within the chamber. The centrifugal force exerted on the particles is proportional to their weight and square of their velocity. The particles slide along the walls of the chamber and gradually circulate down into the conical receptor, while the clean air escapes through a central pipe at the bottom. The dust accumulates in the cone and is discharged continuously or at intervals. The larger the particles, the more efficient the process of their removal. In simple cyclones, particles below 50microns in diameter are not retained, but improved models retain particles as small as 20microns.
Cyclones are used in handling and granulating fertilizers to avoid air pollution and are a safety requirement in the production plants.
