At present, China has a spray dryer common types of dryers, air dryers, fluid bed dryers, fluid bed spray granulation drying machines. A spray drying equipment in progress is one of the fastest equipment, conventional atomization method has three kinds: a rotary atomizer, pressure atomization and gas atomization. Rotary atomizer spray dryer is characterized by a single production capacity (spray volume up 200t / h), the feed capacity is easy to control, operating flexibility, used widely. Pressure atomizer spray dryer is characterized by coarse particles can be made, easy maintenance, due to the nozzle hole is small, easy to plug, it must be strictly filtered liquid feed. Nozzle hole easy to wear, wear-resistant materials must. There is also a new structure of the pressure nozzle, called pressure - flow nozzle. It is characterized as a center pressure nozzle, environmental clearance for airflow around the nozzle. Atomization is divided into two stages: first forming pressure spray film, this film is the second atomizing gas flow, so that finer droplets. The advantage of this type of nozzle (1) adjusting the pressure of compressed air, the droplet diameter can be adjusted, the operation simple. (2) large volume, high-viscosity liquid material can also be atomized into fine droplets. (3) If you disable the compressed air, the original pressure spray can also be used. Nebulizer flow is mainly used for laboratory and pilot plant, its power consumption. The first two atomizer can not atomized liquid material, the use of air-atomizing nebulizer possible. High viscosity paste, a paste material and the filter cake, can be three-fluid nozzle to atomize. Air dryer air drying technology is mature, if the operating data that can be directly designed. Currently, there are a lot of drying equipment manufacturer can provide this type of equipment. Fluidized bed dryer fluidized bed dryer after the spray dryer, into the feeding site of an agitator with a fluidized bed dryer and the heat exchanger of a fluidized bed dryer. When unity is easy to use fluidized bed drying or caking powder materials in the water feeding the larger segment produces fluidized difficult phenomenon, then set the stirrer in the feed zone, eliminating the question of unity, can achieve normal fluidized The latter is conductive and convective heat transfer composition, the amount of hot air is used when the normal flow of the state can not meet the required dry heat, using a heat exchanger inside the set, some or most of the heat supply, which operating modes can be significant energy savings. The heat exchanger has many forms, fluidized bed drying is also often used in combination of the second and third stages dryer. Vibration is applied on an ordinary bed, said vibration fluidized bed. Vibrations stream from the production of the local oscillator can be divided into two categories: one for the vibration motor; the other for ordinary motor to vibrate by excitation box spring. Large vibration fluidized bed size, the better the effect of the latter. The fluidized bed spray granulation process is fluidized dryer technology, spray drying technology and technology combine the three. It is atomized material was sprayed into the fluidized seed already in bed, so that the seed has grown up and dry, to be brought up to the required size when the ejector, but the devices are small, large capacity, capable of producing large particles . Industrial application of this equipment is increasing. 

palabras clave: Fluidized bed dryer, spray dryer, air dryer,