NWB & NWB-HC IM28 OCT 2014
Page 5
Instruction Manual NWB & NWB-HC IM 28 OCT 2014
3.0
PRINCIPLE OF OPERATION
The NWB NovaWheel
™ Series dryer was engineered and designed to effectively remove
moisture (in the vapor state) from hygroscopic plastic resins. This process is
accomplished by the continuously rotating desiccant wheel and the three air streams
(Process, Purge and Regeneration). The Process return air is exposed to an adsorbing
media (desiccant wheel) in a sealed air stream, where the desiccant adsorbs the
moisture from process air. After the desiccant has adsorbed the moisture, it is exposed to
a Regeneration air stream which has been pre-heated to a temperature of about 380°F,
(190°C). This causes the moisture to be driven out from the desiccant and prepares it for
more moisture adsorption. Now the desiccant media passes through third air stream
called purge air stream. Here the desiccant media is cooled down by some of the process
air before entering back into the process to provide for better performance. The three air
streams (process, regeneration and purge) are separated by special Teflon fabric coated
silicon seals. The process air and regeneration air is compressed by using regenerative
blowers.
The dry air from the dryer is then is heated and the air temperature is controlled in an
electric heater, located either in the NovaWheel cabinet on the smaller sizes or this
heater is located at the drying hopper on larger sizes or on a central drying system with
more than one hoppers. The hot dry air enters the hopper at the bottom and dries the
resin in the hopper. The air from the top of the hopper is returned to the dryer, where it is
filtered, cooled in a cooling coil and the process blower sends the air back to the dryer
again to be dried.
