Shown at top left, air from the top zone of the hopper enters the dryer, is filtered, enters a blower, and then is split into two streams. Air in one stream is cooled, passes through the desiccant wheel, is reheated, and travels to the lower hopper zone. The other stream, still warm, requires only minimal reheating before entering the upper zone of the hopper.

Because it adjusts automatically to rate and material variations, a drying system with a wheel-dryer design and airflow pattern enables processors of PET resin to save on plant space, maintenance and energy while obtaining consistent performance.

IntelliPET drying system from Baltimore-based Novatec, requires up to 60 percent less floor space than other wheel-dryer-based systems for PET, and it uses up to 50 percent less energy than conventional systems based on dual desiccant bed dryers, according to Mark Haynie, Novatec's dryer product sales manager. Automated temperature and speed controls adjust to variations in throughput rate, moisture level and material temperature. The design provides the resin at a constant temperature as it exits the hopper, which helps ensure product consistency and eliminate need for operator intervention.

Key components are a desiccant wheel dryer, two-zone drying hopper, electric or gas-fired heater with 90 percent efficiency cyclone, and an optional dust collector.

According to Novatec, one key to the efficiency of IntelliPET is its re-use of heat in the air returning to the dryer from the hopper. Within the dryer, the air is filtered and then enters a blower, beyond which it is split into two near-equal streams. The air in one stream is cooled before passing through the desiccant wheel and subsequently reheated before entering the lower zone of the hopper. The air in the other stream remains at such a high temperature that it requires only minimal reheating before entering the upper zone, thus saving energy, Novatec says.