Novatec Inc. is rolling out a dryer that uses infrared radiation to dry and crystallize PET quickly as the material moves through a rotating drum.
Novatec said infrared drying uses much less energy and is much faster than a conventional, desiccant, PET dryer/crystallizer system. The Novatec IRD can reduce moisture content to less than 50 parts per million in less than 15 minutes — and transforms amorphous regrind or virgin PET into a crystallized form in one continuous operation.
PET goes from a crystalline form of the resin to an amorphous state when it is blow molded into a bottle. So regrind has to be returned to crystalline form before it can be blow molded into a bottle again.
Traditionally, the regrind has to be crystallized first, a process that heats it up and stirs it but does not melt the material, said Novatec Executive Vice President Jack Doub. Then the material moves from the crystallizer to a second machine for drying. The infrared dryer does both steps.
Drying is critical to PET. If the resin is not dried properly, bubbles or spots can appear, causing defects and problems during blow molding.
Desiccant drying can take about six hours, Doub said.
In Novatec's dryer, the material from bottles, sheet or film is fed via a standard Novatec vacuum loader into a large rotating stainless-steel cylinder. Banks of infrared heaters produce the radiation that passes through the air without heating it, so all the energy is concentrated on drying the resin. Radiation actually travels to the centers of the particles, causing them to dry from the inside out. The moisture evaporates, and a stream of room-temperature air is forced through the drum to remove the moisture-laden air.
Newly crystallized PET will be available within 15 minutes, said Baltimore-based Novatec.
A helix welded inside the drum tumbles the material to expose all particles to the infrared heat and move the material forward.
The Novatec unit is available in five standard sizes, to process 400-8,000 pounds an hour. Larger sizes can be custom-engineered. A Siemens touch-screen controller monitors and runs the process.
Doub bullishly said the initial cost of the infrared machine is equal to or less than the cost of a traditional crystalline/desiccant drying system.
“I'm convinced that in 10 years, below 200 pounds per hour will be dried with a membrane system and over 200 pounds, it will be IR. It's just too economical,” he said.
Tel. 410-789-4811, fax 410-789-4638.