What are the technological processes of spray granulation dryer?

Spray granulation dryer is a kind of drying equipment that processes materials such as fluidization, dust removal, atomization and solidification to make them meet the particle size requirements and produce products. The general process flow is that the air enters the bottom of the fluidized bed after being heated by the heater, and contacts with the material through the distribution plate to fluidize the material. The mother liquor or adhesive is delivered to the atomizing nozzle through pressure generating equipment such as a pressure pump. After atomization, it is coated on the surface of fluidized particles or the particles are combined with each other. After continuous fluidization, coating and drying, the particles gradually grow to the required particle size, and then are discharged from the outlet of the fluidized bed. Widely used in chemical industry, medicine, food and other industries.

The pressure spray granulation dryer is mainly composed of feeding system, drying system, dust removal system, heating system and electrical system, and each system includes some related equipment.

The feeding system consists of a mixing barrel, a filter, a diaphragm pump and a spray gun. The secondary slurry after ball milling is transported from the ball mill to the mixing barrel, pumped and transported by the diaphragm pump through the filter, and then enters the drying tower through the spray gun.

The slurry enters the drying tower from the nozzle of the spray gun and starts the spray granulation drying process, which is divided into three stages:

1, slurry atomization

The slurry is pressed into the drying tower from the nozzle by the diaphragm pump in the feeding system under a certain pressure, and the energy of the pressure is converted into kinetic energy, and the slurry is ejected from the nozzle from bottom to top, forming a high-speed liquid film and then splitting into droplets. The droplet size produced by atomization is inversely proportional to the pressure, and the production capacity of the nozzle is directly proportional to the square of the pressure.

2, drying the atomized particles into balls.

Fog drops and hot air work in a mixed flow mode, and the hot air enters the tower through the hot air distributor on the top cover, which generates downward streamlined airflow, and the fog drops are sprayed into the hot air flow from bottom to top. The droplet is spherical due to surface tension, and at the same time, due to the large surface area of the droplet, the water in it quickly evaporates and dries, and finally shrinks to form dry spherical particle powder.

The spherical particle powder formed gradually settles in the drying tower and is separated from the hot air. The funnel-shaped cavity at the lower part of the tower enables the granular materials to gather and be discharged from the discharge port. Fine-grained materials are sucked together with dry air by an exhaust fan connected to the funnel-shaped upper part and enter the dust removal system.

3, discharging the granular powder

The drying system consists of a blower, a drying tower and an exhaust fan that delivers hot air to the drying tower.

The dust removal system consists of high-efficiency cyclone separator, bag filter and centrifugal fan. The exhaust fan sends the finer particles into the high-efficiency cyclone separator together with the dry air. After effective separation, the finer particles enter the collection cylinder at the bottom of the separator for recovery, and the remaining waste gas containing a very small amount of fine particles is sucked into the bag dust collector by the centrifugal fan for dust removal and collection again, thus realizing the harmless treatment of the waste gas, and finally the waste gas is discharged from the chimney.

In addition, a heating system consisting of an electric heater and a gas-fired hot stove provides hot air for the drying tower. The electrical system consists of an electrical control cabinet and field sensors installed at the air inlet and air outlet, which are used to monitor the temperature and all the main links of the whole spray granulation dryer to ensure the normal operation of the whole equipment.