Applications

• Crystallising and drying of PET regrind from sheet, film or bottles

• Drying of virgin PET

• Pre heating and drying of free – flowing powders

• Pre heating and drying of wood / PP

• Blends of regrind, virgin and additives

• Biodegradable PVOH

• Hygroscopic thermoplastics

Energy Saving - Power Consumption Comparison

• Due to the speed of moisture removal by IR acting directly at the core of the material energy consumption is low.

• Typically for PET the power required is 120 watts per kilo per hour.

Infrared drying offers a 64% power saving over conventional drying

Infrared Drying With Plastics - How can it be that fast?

The Difference

Step A : Energy Source

Convective Drying

Infrared (IR) Drying

Heat conducts into the pellet.
Plastic is a poor heat conductor.

Heat is adsorbed inside the pellet.
Plastic and water are excellent IR adsorbents.

How the Water Reacts with Convective Heating

Vapourised water moves to the coolest area!
Convective heating starts at the surface of the pellet and slowly heat is conducted towards the centre.

In this phase the moisture is attracted towards the cooler
centre of the pellet!

Drying does not even start.

What is more the moisture concentration inside the pellet increases!

How Moisture Reacts to Infrared Heating

Water vapour moves to the coolest area!

IR heating starts inside the pellet and immediately heat is
conducted towards the cool ambient air.

In this phase the moisture is heated and vapourised
immediately and is attracted out of the pellet into the cooler ambient air.

Step B : The Separation of Moisture from Material

 By Convective Heating

• When the entire pellet has reached the same temperature as the hot ambient air drying starts.

• Vaporisation rate is low.

• Vaporised water is transported from the core of the pellet to the surface.

• The driving force for this diffusion is a difference in partial pressure of the ambient air.

• To ensure this process is effective desiccant air with a low dew-point is applied generally.

• The diffusion driven by partial pressure is a slow process!

 By Infrared Heating

The physical force for moisture diffusion is a difference in temperature and a difference in partial pressure!

• IR- provides a high vaporisation rate on moisture in the core.

• The driving force for diffusion is a difference in Temperature between the vaporised moisture and the ambient air.

• IR uses cool ambient air so a permanent difference in partial pressure is always available.

• Diffusion driven by temperature and partial pressure is a very fast process!

The UPM Infrared Rotary Drum

DRY YOUR MATERIAL - The Direct Way

Radiant Heating - Automatic Operation

Material is conveyed to the inlet of the IRD which incorporates an internal helix so as the drum rotates material is gently transported through the length of the drum passing under an infrared radiator and discharging out to the process.

The application will dictate the drum diameter and length together with the power of the radiator.

The final moisture content is a function of the residence time and temperature which are controlled automatically by the drum RPM and infrared power.

Contact UPM about the Infrared Drying product range