| 摘要 |
<PICT:0872334/III/1> In the spray-drying of liquid solutions or suspensions or of filter cake, a collecting member is arranged in the drying chamber in the path of the sprayed particles at a point where drying is well advanced, and material adhering to the member is removed mechanically, by vibrating; larger particles are thus obtained than if the particles are completely dried. The liquid or filter cake to be dried, e.g. a suspension of a dye, is sprayed by stationary nozzles or by means of the rotating disc 12. Hot air flows through the duct 16 and dries the particles. The collecting member 24 may be a sieve having a fine mesh, e.g. of the same order as the particles striking it, or may have a roughened, e.g. sand-blasted, surface. With the usual round drying tower the diameter of the collecting member should be at least half the diameter of the tower. The member is periodically or continuously vibrated, e.g. by magnetic means 26. The member is also preferably periodically moved slowly in a direction transverse to the plane of the sprayed particles, i.e. in the direction of the arrow 28. In an example using a laboratory spray-drier 60 centimetres long and 27 centimetres in diameter and using a nozzle spray, a metal sieve, mesh size 0.3 mm., is arranged at about the middle. Without the sieve, in drying a suspension of a dye, particle sizes of 0.20 mm. are obtained; with the sieve which is vibrated every 3 seconds, particles of 0.30 mm. are obtained. |
