A step change for recycling
Increased centrifuge throughput in plastic recycling with innovative screw conveyor
Recyclers of post-consumer and postindustrial plastic materials rely heavily on decanter centrifuges. But the processing of shredded plastics into several fractions is not always a simple task. Excessive or varying feed rates can lead to regular blockages. And a blocked feeding system must then be stopped, flushed, and cleaned. All of which leads to significant production losses and additional manpower requirements.
The challenge:
Improve productivity and reduce downtime at recycling centrifuge
To resolve this, ANDRITZ SEPARATION decided to design and manufacture a new screw conveyor for the existing CENSOR decanter that would:
- Substantially reduce downtime due to feeding system blockages
- Enable increased feed/production rates
- Reduce potential mechanical wear as a result of increased feed rates
The upgraded screw conveyor, retrofitted into current decanter centrifuges, has been undergoing trials at multiple customer locations since October 2015. Following successful on-site trials, the new screw conveyor design is intended to be available as an upgrade to existing CENSOR decanters as well as in new, integrated decanter centrifuge designs.
Our solution:
A high-throughput, low-maintenance screw conveyor design
The upgraded decanter began initial onsite tests in the fall of 2015, and expectations were high among both plant managers and the ANDRITZ SEPARATION specialists. The initial aim was to increase production by at least 30% while lowering maintenance and repair costs in relation to annual recycling tonnage.
It became clear during the design phase of the new screw conveyor that considerable production gains could be achieved. This necessitated new features to reduce wear resulting from the higher feed rates. Thanks to these adjustments, the on-site trials proved that downtime and personnel hours related to clogging could be
considerably reduced, and an extended lifetime – measured in annual tons – could be expected.
Results:
Up to 80% higher production, 20% lower maintenance costs
Depending on the combination of product features and peripheral systems on site, the multiple trials proved that the redesigned screw conveyor could help the decanter to achieve a production increase of up to 80%. Maintenance and repair costs per annual ton of recycled plastic were also reduced by approximately 20%.
The results, needless to say, greatly exceeded the customers’ expectations. The first upgrade package sold in December is currently estimated to pay for itself within six to ten months, depending on actual production quantity. This is nearly equivalent to having an extra CENSOR decanter in production, at just a fraction of the upfront investment cost.
