Automated Conveying for Efficient Optical Sorting of Recycled PET – Novelplast

The Challenge: Maintaining Quality and Consistency in Post-Consumer PET Recycling

Novelplast sources post-consumer PET from suppliers around the world, accepting material in multiple forms including flake, fiber, fines, film, sheet, regrind, and purge. Running two extrusion lines up to 24 hours a day, five and a half days a week, material quality directly affects output.

Their customers require recycled plastic to meet strict specifications for intrinsic viscosity (IV) and haze. Contaminants such as mixed colors, foreign polymers, sand, and metal vary from batch to batch and, when present in the feed material, cause filter blockages and unplanned downtime.

To control input quality, Novelplast invested in a Tomra Innosort Flake optical sorting system, targeting a final purity of over 95%. While Tomra supplied the sorting technology, Novelplast still needed an efficient way to convey material to and from the sorter and manage the multi-pass process required to reach the target purity.

Engineering Manager James Farrelly was responsible for finding a conveying solution that could make the sorter work in practice. The system needed to fit within the existing production space, stay below a 6.5-metre height limit, and achieve a throughput requirement of one tonne per hour.

The Facts: Material Specifications and System Requirements

• Material: Post-consumer PET from global suppliers
• Material forms : Flake, film, fiber, sheet, fines, regrind, purge
• Sorting technology: Tomra Innosort Flake CRGB NIR
• Target output purity: 95%
• System Requirements:
  • Handle up to 1 tonne per hour
  • Support filtration down to 200 to 300 microns
  • Remove color contamination, foreign polymers, and other reject material
  • Direct clean and reject material to separate destinations automatically
  • Operate within existing space and height constraints (below 6.5 metres)
  • Perform consistently in a 24/5.5 production environment

The Solution: Pneumatic Conveying for Multi-Pass PET Optical Sorting

After evaluating several options, Novelplast selected Kongskilde to design and deliver the complete conveying system.

The final solution is built around two core components: MultiEvacuators and Rotary Valves.

1. MultiEvacuators – Six pneumatic conveying systems positioned around the Tomra move PET flake through each stage of the sorting process, all managed through a single control panel.
2. Rotary Valves – Seven rotary valves control metered feed and discharge at each transition point, keeping clean and reject streams fully separated.

How the System Works

• Incoming material is fed into hopper one and released through track one
• Material that passes moves automatically to hopper two for a second sort
• Reject material from tracks one and two is directed to hopper three for a third pass
• Material passing track three re-enters the process at hopper one
• Only material that fails all three passes is directed to the reject bag
• Finished goods advance automatically to the bagging station

The final solution provided Novelplast with a compact and reliable way of managing a complex, multi-pass sorting process. The system fit within the existing warehouse space, required minimal maintenance, and integrated seamlessly with the new Tomra sorter.

Advantages & Benefits: Automated PET Conveying for Consistent Recycling Output

Fully automated multi-pass sorting

A complex three-track sorting process runs without manual intervention between passes, reducing the demand on operators and supporting consistent production output.

Consistent material quality

Higher input quality gives Novelplast greater consistency in meeting the intrinsic viscosity and haze requirements of their customers.

Reduced extrusion line disruptions

Cleaner input material has resulted in fewer filter blockages, improving uptime across both extrusion lines.

Space-efficient design

The conveying system was engineered to fit within the constraints of an existing production facility, working within strict height and floor space limitations without requiring structural changes.

Seamless integration

Kongskilde selected and configured the ideal components for integration with the existing equipment, ensuring a smooth start-up.