Crystallizers
By Mark Haynie and Joshua Belisle · Edited by Dana Gardner
Published August 7, 2024 · Reviewed by Mark Haynie · July 20, 2026
Summary
What does a crystallizer do for PET reprocessing?
A crystallizer converts amorphous PET back to a crystalline state so it can be reprocessed; technically it is not a dryer. Material is loaded into an insulated hopper, heated, and agitated to prevent agglomeration. Crystallization can take from a few minutes up to about an hour depending on the material, after which the material goes to a drying hopper before processing.
Technically, crystallizers are not dryers. They are used to convert PET from an amorphous, back to a crystalline state for reprocessing.
The crystallizer consists of an insulated hopper with an agitator driven by a gear motor and a heater/blower. Amorphous material is loaded into the top of the hopper and is heated to about 180˚ F. while being agitated to prevent agglomeration.
The crystallizing process in a typical crystallizer can be and must be monitored carefully for success. Crystallization may occur in a few minutes up to about an hour, depending on the properties of the material being crystallized. Upon completion, the re-crystallized material, discharged from the base of the hopper may then be transported to a drying hopper where it is dried by a dual bed or desiccant wheel drying system. Then it can be processed into new products.
NOTE: The infrared drying system is a new technology gaining rapid acceptance for crystallizing and drying PET. You can accomplish both operations in one step in one hour with greatly reduced energy usage.
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Technically, crystallizers are not dryers. They are used to convert PET from an amorphous, back to a crystalline state for re-processing.
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Frequently Asked Questions
What are the main parts of a crystallizer?
A crystallizer consists of an insulated hopper, an agitator driven by a gear motor, and a heater/blower. Amorphous material is loaded into the top of the hopper and heated while the agitator keeps it moving to prevent agglomeration. Once crystallization is complete, the material is discharged from the base of the hopper.
How long does PET crystallization take?
Crystallization may take anywhere from a few minutes up to about an hour, depending on the properties of the material being crystallized. Because the time varies, the process must be monitored carefully to succeed. Once complete, the recrystallized material is discharged from the hopper and moves on to drying.
Does crystallized PET still need to be dried?
Yes. A crystallizer is not a dryer. After crystallization, the material discharged from the base of the hopper is transported to a drying hopper, where it is dried by a dual bed or desiccant wheel drying system. Only then is it processed into new products.
About the Authors
Vice President of Moisture & Drying Technologies, Novatec
Mark Haynie has designed and installed resin drying systems for more than 40 years, working in thousands of plastics plants across the industry. As Novatec’s Vice President of Moisture & Drying Technologies, he leads the company’s drying technology group, including its work on moisture measurement and predictive drying. He also serves as a technical reviewer for Novatec’s Drying Knowledge Center and has authored numerous technical articles and whitepapers on resin drying and moisture.
Mark earned a Bachelor of Science in Chemical Engineering from Virginia Tech.
Through Novatec’s Ask the Expert program, Mark regularly helps processors troubleshoot drying performance and resin-moisture challenges.
Technology Manager, Novatec
Joshua Belisle is Technology Manager at Novatec, where his work focuses on simulation and technology development for resin drying. He earned a B.S. in Mechanical Engineering with a minor in Engineering Business from the University of Virginia in 2023 and joined Novatec that same year. Joshua uses simulation tools to investigate previously difficult-to-measure aspects of the drying process, helping Novatec better understand airflow, heat transfer and other variables that influence resin-drying performance.
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Author Profile:
Mark Haynie has designed and installed resin drying systems for more than 40 years, working in thousands of plastics plants across the industry. As Novatec’s Vice President of Moisture & Drying Technologies, he leads the company’s drying technology group, including its work on moisture measurement and predictive drying. He also serves as a technical reviewer for Novatec’s Drying Knowledge Center and has authored numerous technical articles and whitepapers on resin drying and moisture.
Mark earned a Bachelor of Science in Chemical Engineering from Virginia Tech.
Through Novatec’s Ask the Expert program, Mark regularly helps processors troubleshoot drying performance and resin-moisture challenges.