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machinery feature | Melt filtration


Gneuss says its RSFgenius M


can cope with even higher


contamination rates than previous models


nization of the drive and back-flushing mechanism. This is claimed to further optimize the self-cleaning technology, resulting in a significant increase of screen capacity as well as a reduction of the quantity of material lost through backflushing. Gneuss cites the


use of the RSFgenius M filtration systems at two recycling applications in South America. At the company Brandt in Brazil, an RSFgenius M 150 replaced a slide-plate screen-changer on a 380 kg/h repelletizing line. This extruder processes 100 % PP and PE reclaim into pellets for injection moulding. With the line in its original configuration, Brandt


reduced disruptions caused by frequent screen-chang- es by not processing the most contaminated materials. Now, it processes everything, and with no disruptions for screen-changes output has been increased by around 1,000 kg/day. At the same time, thanks to finer screens, the end product quality has been increased, Gneuss says. Meanwhile, at Reteplast in Argentina an RSFgenius


Nordson Kreyenborg’s new filter cartridge is bringing


benefits on a high-through- put PET recycling line


M 150 replaced a slide-plate screen-changer on a 400 kg/h repelletizing extruder. Here, 100 % reclaim, mainly PP, ABS and PE, is processed into pellets, also for injection moulding applications. In the past, the material had to be washed before the


extrusion process in order to separate paper contami- nation. With the RSFgenius M, this extra step is not necessary any more. The melt is now automatically filtered to 250 microns, without any disruptions or disturbances.


The RSFgenius M automatically backflushes the


screens 350-500 times, depending on the specific mate- rial. The material losses through backflushing are considerably lower than the material losses caused by more than 200 screen changes per day needed with the slide-plate screen- changer. Daily output has increased by 30 % and end-product quality has also improved. Nordson PPS says a new


screen-changer filter cartridge designed to resist deformation and enhance polymer flow has enabled the operator of a high-throughput PET


60 COMPOUNDING WORLD | July 2015


recycling line supplied by Starlinger to reduce the frequency of filter replace- ment and improve pellet quality. Installed in a “bottle-to-


bottle” recycling line at a European company, Star- linger’s Recostar PET 165 HC iV+ recycling line includes a Nordson Kreyen-


borg K-SWE-4K-75/RS screen-changer situated between the extruder and the underwater pelletizer. The line operates continuously every day of the year, producing


rPET with intrinsic viscosity levels that are varied according to the application. When Starlinger’s customer replaced a standard


filter medium in the screen-changer with the new filter cartridge, the filter life was lengthened from eight to 72 hours, according to Christian Lovranich, head of process engineering at Starlinger recycling technology. Besides prolonging filter life, the design of the new


filter cartridge also addresses the requirements of high-throughput systems such as the 1,400 to 1,600 kg/h Starlinger line. “The larger filter area of the cartridge and the elimination of stagnation zones reduce pressure variations that can detract from pellet quality,” says Lovranich. “In addition, there is less material lost in backflushing, and there are no metal impurities.” A 40% reduction of the backflush amount compared


to the previous system (a conventional backflush filter) was also realized, the company says, leading to a short pay-back of the replacement investment. The available filter area is 1,672 cm2


and the filtration fineness is 50


micron. The robust structure of the new filter cartridge


prevents pressure loss and deformation of the steel filter fabric, enabling it to withstand the high mechani- cal stresses encountered during production start-up, notes Christian Schröder, research and applications engineer for Nordson PPS. Schröder says that the new filter cartridge is an


alternative to standard filter discs, in which surface area is increased through pleating of the filter fabric. “The pleating makes the fabric susceptible to mechani- cal stresses, which can reduce the efficiency of melt filtration by causing the pleated layers to be pushed together or squeezed during processing,” he says. “This also reduces the working life of the filter.” Maag Automatik has also been concentrating on


increasing filtration capacity without adding to space requirements. Maag Pump Systems and Automatik Plastics Machin-


www.compoundingworld.com


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