Drying a Popular Plastic
At its Cooper River plant in Charleston, South Carolina, DuPont produces high-performance Hytrel polymer for many applications. The global chemical and plastics giant sells Hytrel in the form of pellets as a raw material to OEMs, who then fabricate it into a multitude of consumer products. Applications are mostly for the automotive industry, ranging from constant-velocity joint boots to covers for air bags. Hytrel works well for these types of parts because of its superior cold-weather properties.
To achieve the highest quality, DuPont goes to great lengths in its production process to dry the pellets by running fresh, hot air through them. A roof-mounted Munters manufactured Wringer® dehumidification system provides the required dry air.
The Wringer® condenses moisture out of the air by cooling it with mechanical refrigeration to a dew point of 45ºF. Energy use is optimized as outside air and cool air from the refrigeration coil pass through opposite sides of a counter-flow air-to-air heat exchanger. Heat recovery takes place to precool the warm air coming in (94ºF is used as the summer design condition) to 68ºF, and it reheats the cool air back up to 83ºF for drying. This reduces the tonnage of the equipment required for cooling and dehumidification, and it saves energy as well.