Nodulizing and Drying Drums
Nodulizing and drying drums are designed to dry pulp, yielding a finished product in the form of granules.
A nodulizing and drying drum is a cylindrical body tilted toward the unloading side, supported by shrouds on two support stations, and rotating from the drive at a speed of 3-5 rpm. The drum is equipped with a loading and unloading chamber.
The principle of nodulizer/drier operation is as follows. When the drum rotates, the lifting flights 8 create a stream of material that pours from the blades. The pulp of the granulated substance is sprayed on the material stream by the pneumatic nozzle 12, which, when layered onto particles, increases their size. Wet agglomerates roll over the inner elements of the drum, acquiring a spherical shape, and dry in the flow of the heat carrier.
The nodulizing and drying drum equipment, including a classifier, made in the form of a cone 7, is installed in the unloading zone. The large fraction accumulates at the narrow base of the cone and is unloaded from the equipment. The fine fraction that has accumulated at the large base of the cone returns to the spray zone of the pulp by the reverse auger in the form of an internal recycle. The dust from the cyclones and the material after the crushers can also be fed here in the form of an external recycle.
The efficiency of the nodulizing and drying drum equipment operation is significantly influenced by the density and uniformity of the material being poured in the pulp spray zone, the operating parameters of the spray nozzles, the speed of the heat carrier, and other parameters.
To intensify the granulation and drying of fertilizers in the nodulizing and drying drum equipment, a number of technical solutions have recently been proposed, the essence of which involves the intensification of heat-mass exchange processes occurring in the nodulizing and drying drum.