OPERATIONAL SEQUENCE (EVS)

 
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The drying system essentially employed in conjunction with an underwater pelletizer, consists of two (or three) vibrating screens (drying modules) arranged in series. The first drying module involves the preliminary dehydration of the pellets. The process water is separated from the pellets in a pre-dewatering unit prior to being delivered to the vibrating screen; the water is then filtered and diverted into a water tank from which it is pumped to the underwater pelletizer, completing the process water recycling loop.

The actual drying of the pellets takes place in the second drying module which immediately follows. This drying screen is executed with axial blowers and air-water heat exchangers beneath the screen generating an upward air current. This design ensures the air only flows in through the heat exchangers, which are exposed to the thermal energy of the process water which is transported by a recirculation pump. The energy input of the hot process water warms the incoming air sufficiently to dry the pellets. For the drying of hygroscopic materials with a high degree of dehydration the system can include controllable heater coils together with a third vibration module.

In order to utilise the energy gained from the pellets most effectively and efficiently the speed of the axial blowers can be regulated, contributing further to the highly economic efficiency of the drying system.