Vacuum Dryers

[Throughputs up to 1000 lb./hr.]

Vacuum Dryers do not utilize desiccant and there is no dew point reference for the process air. Instead, they use a very strong vacuum to draw moisture away from warm pellets.

Vacuum dryers use a multi-stage process. In the small dryers (up to about 100 lb./hr.) Plastic pellets are contained in a stainless steel sealed vessel that rotates between three stations, staying in each position for about 20 minutes. At the first station, the vessel is filled with pellets and they are heated to allow the molecular release of moisture. In the second station, they are repeatedly subjected to a strong vacuum, to draw away the moisture.

The dried pellets are discharged at the third station. This simplified process affords users fast drying with less energy consumption than most alternatives. The process is, by nature, a batch process so the material is loaded, processed, then dumped, and the cycle repeats.

There are larger vacuum dryers with drying throughput capacities of up to 200 lb./hr. and up to 1000 lb./hr. These models use a vertical configuration where the resin is loaded into an insulated hopper (at the top of the unit) where it is heated. Then the resin drops into a vacuum vessel where the moisture is removed. After the resin is dry, it drops int a retention hopper and transferred to the process machine. The whole process takes less than an hour and uses about 1/6 the energy of conventional dual bed desiccant dryers.

Novatec Ultra Vacuum Dryers are an efficient, low-energy method of drying a range of plastic resins.

Types of Resin Drying Systems

Silo Dehumidification/ Hot Air Dryers

What is a silo dehumidifier and how does it work and compare with other resin drying systems?

Compressed Air Dryers

The principle of compressing air in factories for power tools and other high-pressure uses has a side benefit for the world of resin drying.

Membrane Dryers

What is a membrane resin dryer and how does it compare to a compressed air dryer without a membrane?

Vacuum Dryers

What is a vacuum resin dryer and how does it draw moisture away from plastic pellets in vacuum processing?

Dual Bed Dryers

Dual Bed (also called Twin Tower) dryers used to be the most commonly purchased type of resin dryer. A look at why, and where the technology has progressed.

Desiccant Wheel/Rotor Dryers

The advantages of desiccant wheel dryers include operating at a low temperature, which is important for preventing thermal degradation of the resin.

Crystallizers

Technically, crystallizers are not dryers. They are used to convert PET from an amorphous, back to a crystalline state for re-processing.

Drying Hoppers for Plastic Resins

Drying hoppers are part of most drying systems. At a glance, they look much the same, but there are certain features you should look for.

Gas-Fired Process Heaters

What are the benefits of gas-fired process heaters for drying plastic resins?

Portable Resin Drying Systems

Resin drying machines that can be moved from machine to machine within a plastics processing plant have advantages and disadvantages over a central drying system.

Central Resin Dryers

Properly designed Central Drying Assemblies are easily connected together to save installation costs.

PET Energy-Saving Drying Systems

Learn about the keys to drying PET efficiently while saving space and energy.

Ask the Expert

Mark Haynie Vice President, Moisture & Drying

Submit A Question

Novatec, Inc.

410-789-4811 | 800-237-8379

http://www.novatec.com

 
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