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Infrared Dryers

Question:
Is the IRD system proven in the market?

Response:
There are about 250 IRD systems in the field now and the use is very favorable in areas where the electric rate is good and also best where natural gas is not a preferred heating method.  We can provide you with an economic analysis to help determine if an IRD system makes sense for your plant.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
We have not seen the performance of the IRD as advertised.

Response:
Optimum performance of the IRD requires that it has a buffer hopper to allow the performance to be uniform.  It provides the time necessary for the final amount of moisture to leave the flake as well as provides a surge capacity to the extruder.  Some manufacturers sold IRD’s without a buffer hopper and this may account for your experience. The other important part is having uniform temperature control and air flow in the drum.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
If you need a buffer hopper, doesn't that defeat the purpose of going to IRD?

Response:
No.  The buffer hopper typically only has 30-60 minutes of residence time as compared to 4-6 hours in a typical dryer hopper.  Since the hopper is small and most of the moisture is removed prior to the buffer hopper, the air flow necessary is also quite small in comparison to a typical drying hopper.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
Does the buffer hopper require heating?

Response:
Yes.  The buffer hopper has 30-60 minutes of in-process material and a low heated air flow, provided by a small desiccant wheel dryer, compared to traditional drying systems.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
Does infrared drying allow you to bypass the crystallizing step? 

Response:
No.  With infrared drying the crystallizing and drying both occur in the drum.  There is a temperature profile in the drum such that the resin/flake crystallizes in the first ¼ to ½ of the drum and continues to dry until the outlet.  The rotation of the drum allows the flake to stay in motion and thus eliminate the formation of lumps as the resin goes through glass transition (crystallizes).

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
Can the IRD be used as central crystallizing-drying system? How many buffer hoppers can be used per IRD units?

Response:
Yes, however, it is sometimes an expensive crystallizer.  The best payback is when it is used to both crystallize and dry.  As far as buffer hoppers it is usually best to use one buffer hopper with multiple take-offs when the IRD is serving multiple extruders.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
What about high dust content in PET flake going through an IRD?

Response:
As with all systems, dust can be an issue.  Dust can be limited with proper maintenance of the grinders and even the use of cyclones to remove some of the fines.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

Question:
Can an IRD handle PETG and amorphous PET?

Response:
The IRD can handle amorphous PET (APET) but is not usually used for PETG since it doesn’t require tradition   This is why its use has been primarily in PET.

Mark Haynie: Drying Systems Product Manager, Novatec, Inc.

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