Sustainable drying and crystallisation with infrared
Is the IR technology known from preform heating also an alternative for drying and crystallising virgin and/or rPET flakes? We spoke to Udo Gielen, CEO, and Marcus Vogt, Technical Sales Manager at Kreyenborg in Senden, Germany. The company has been working on this technology for over 20 years.
Interview with Kreyenborg GmbH & Co KG // August 14, 2025
We met: Udo Gielen, CEO and Marcus Vogt, Technical Sales Manager
Photo top: F.l.t.r.: Udo Gielen (CEO Kreyenborg), Marcus Vogt (Technical Sales Manager) and Alexander Büchler in front of an open drum. The material is continuously rolled past the infrared elements.
Tradition and specialisation
Kreyenborg was founded in Münster, Germany, in 1953 and has been active in the plastics sector since 1966. The company became known for its machines and systems in plastics recycling. The first melt filter went into operation in 1967. Kreyenborg set another milestone with the launch of the infrared rotary drum (IRD) in 2004. In 2013, the US company Nordson took over some of the company’s divisions – since then, Kreyenborg has been able to concentrate fully on IR technology, its components and the established construction of mixers and special silos for the recycling industry.
Drying in the infrared rotary drum is used both in food technology and in the plastics industry. In the plastics sector, the focus is clearly on the drying and crystallisation of virgin and recycled PET besides other plastics.
Functional principle
Unlike conventional dryers with hot air or vacuum crystallisers, the Kreyenborg technology does not require either. The infrared light penetrates pellets or flakes and heats them evenly from the inside and outside in just a few minutes. A rotary drum keeps the material in continuous motion, so that it heats up evenly without clumping together.
Between the individual infrared heating zones, the system measures the surface temperature of the PET inline and can therefore react directly to changes in the material. Marcus Vogt describes the efficiency of infrared compared to hot air vividly: “Try frying a sausage with a hot air dryer – or over a coal fire.”
Performance and quality
Kreyenborg has continuously developed the IRD technology for many plastics – and has created a separate business unit (IR-Clean) specifically for PET. With different IRD sizes, throughputs of 20 kg/h to 2.5 t/h can be realised – with initial moisture levels of up to 10,000 ppm. The material leaves the IR-Clean unit with a residual moisture content of less than 500 ppm and a purity that complies with US FDA specifications. Recycled PET flakes can be processed directly inline in the extruder into films and sheet for food contact.
Since the requirements in the European Union are higher, the decontamination efficiency must be increased again for EFSA: a further dryer (finisher) is used after the IRD, which extends the residence time under temperature to increase the decontamination efficiency. In this configuration a cleaning efficiency of more than 95% can be achieved, allowing the use of up to 100% rPET in food packaging with a shelf life of 365 days at 25 °C. As a side effect, the residual moisture is reduced below 50 ppm.
Advantages over conventional methods
CEO Udo Gielen explains the differences from classic hot air or vacuum technology:
“You don’t need any pipework, cooling, vacuum or compressed air for the process – just a power connection. This saves a lot of effort and makes the technology safer and simpler. The direct thermal coupling of the IR heat with the PET eliminates the diversions via the heating coil and air, which significantly increases efficiency.”
Vertical integration as a strength
Kreyenborg also attaches great importance to the high level of vertical integration at the Senden site: from the laser cutting system to separate halls for stainless steel and black plate through to final assembly – everything takes place on site. Around 400 IRD for plastics are now in use worldwide, of which around 70% are for PET.