MACHINERY | PELLETISING SYSTEMS
Above: Coperion Pelletizing Technology’s SP cutting chamber features an optimised cutting tool arrangement to improve cut quality and cleaning
and there is strong demand for increasing recy- cling rates. New potential growth areas are the production of micro-pellets for use in 3D printing and a recent increase of biodegradable materials.” Higher levels of contamination in feedstocks
Right: Nordson says water ring pelletisers such as its BKG WRP 1000 offer advantages over strand alternatives
from recycled materials brings new challenges in terms of melt filtration. “A fine filtration with minimum material losses is key to meeting these challenges,” says Asmuss. “In addition, energy consumption is increasingly being considered by companies investing in pelletising systems. Besides new features for all types of pelletisers which improve process stability, handling, energy efficien- cy and productivity, the ‘core’ of each equipment system is still the most important detail to take into consideration; by that I mean the die plate design for pelletisers, and the filter medium for melt filters.” Nordson has developed a range of BKG systems for pelletising, including a complete system for producing virgin-like rPET from PET bottle flake. “Regulatory and market mandates call for a dramatic increase in use of rPET in the major markets - fibres, bottles and films. Our product line for rPET com- bines the next generation of BlueFlow gear pumps, HiCon V-Type 3G+ screen changers and BKG underwater pelletising systems. Included are the new FlexDisc filters for finer filtration at lower material losses and the CrystallCut system for energy-saving inline crystallisation. Of course, using the latest developments in die plates offers the longest lifetimes for changing raw material qualities,” he says.
Strand alternative Asmuss adds that, while water-ring pelletisers (WRP) are not appropriate for lower-viscosity materials such as PET, they provide advantages over strand pelletisers in processing a wide range of polyolefin and styrenic materials. The
46 PLASTICS RECYCLING WORLD | January/February 2021
www.plasticsrecyclingworld.com
company’s latest generation WRP — the BKG WRP 1000 —includes a number of improvements adapted from its well established BKG underwater pelletisers. “The compounding and recycling industries are moving away from strand pelletising because it is labour intensive, has a substantial footprint, gener- ates dust, tends to yield pellet inconsistencies, and provides little scope for automation,” says Asmuss. “The BKG WRP 1000 water-ring pelletiser eliminates these problems for a capital investment that is mid-range between that of a strand pelletiser and our more high-performance underwater systems.” Nordson says that, compared to equivalent strand pelletisers, the new WRP design is more compact, generates less dust, is more capable of automation, and yields pellets of more uniform shape and size. Obviously, strand breakage is eliminated. Key features of the WRP 1000 include a split- design die plate with separate heating flange and easily exchangeable insert, which is said to make for rapid colour changes and easy cleaning. The die plate is heated with electrical heating cartridg- es and is designed for uniform polymer flow in the die plate holes. The centrifugal drying system is adapted from the established pellet dryer design used for BKG UWPs. The company says it provides low moisture levels in the pellets, noise levels of below 85 dB, and easy maintenance access doors. The WRP 1000 provides a maximum throughput
of 1,000 kg/hr and can operate at pressures up to 210 bar and temperatures of 320°C. It can be used to process a wide range of olefin and styrenic polymers and copolymers with densities up to 1.5 g/cm3
,
including moderately filled formulations. Die plates are tailored to the specific material to be processed and the machine is available in a pre-wired version without control for system-integrators, or as a stand-alone PLC-based system for independent operation or upgrading of existing lines.
IMAGE: COPERION
IMAGE: NORDSON
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