Extrusion 4-2017

large woven wire-mesh screen that periodically must be re- moved and cleaned manually. • BKG ® Combi Series : new water-filtration options. BKG ® Combi-Line™ systems, also with capacities up to 2,000 kg/hr, combine all of the features of the BKG ® Master-Line™ system and are available with an optional curved fines removal sieve. More advanced is the BKG ® Combigon™ system, which incor- porates the BKG ® Polygon™ automatic filter as standard equip- ment and is available with an optional belt filter. • BKG ® Opti Series : top-of-the-line water system. Available in models with capacities ranging up to 15,000 kg/hr. BKG ® Opti- Line™ systems include noise reduction of the centrifugal dryer, pre-dewatering to enhance dryer efficiency, dryer window and lights, and self-cleaning of the centrifuge. Also available as an option is a curved fines removal sieve. Larger-capacity systems are available on request. A more advanced system is the BKG ® Optigon™, which comes with the BKG ® Polygon™ automatic filter as standard equip- ment and is available with an optional belt filter. BKG ® Polygon™ filtration system: key to energy savings The BKG ® Polygon™ water filtration system is an automated, self-cleaning, tempered water system that minimizes operator intervention and reduces overall pelletizer energy consumption by ten to 17 percent. One key to these benefits is the elimination of the need for a separate fines-removal sieve, which in standard systems re- quires a secondary, dedicated water pump. Instead, all filtration is provided by a Polygon drum filter, which due to the large fil- tration area can be equipped with 70-µm screens compared to 150-µm screens used in standard systems. Driven by a small motor, the drum rotates within the water that is circulated throughout the pelletizing system by the main process water pump. The filtration system is designed so that dirt and fines stay confined inside the drum until they are evacuated into a collecting basin outside the tank. In effect, a small motor plus gravity facilitates the fine filtration of the process water. By eliminating the secondary pump, the BKG ® Optigon™ water filtration system uses only 1,440 KW per year (measured at 8,000 hours), as against 44,000 kW for the BKG ® Opti-Line™ system with curved sieve. Since water filtration typically ac- counts for ten to 17 percent of the energy consumption in un- derwater pelletizing, the energy efficiency of the BKG ® Opti- gon™ system means that overall consumption is cut by nearly that much. Substantial energy cuts in PET production A patented process developed by Nordson specifically for PET production dramatically reduces energy costs by producing and crystallizing pellets in a single integrated process. Called BKG ® CrystallCut ® , the process uses the thermal energy of the molten polymer in PET pelletizing for subsequent crystallization, avoid- ing the need to cool PET after pelletizing and then reheat it for crystallization. As an integrated network that incorporates underwater pelle- tizing, drying, and crystallizing, the BKG ® CrystallCut ® process is designed for precise control of material temperatures throughout the process, preventing production and quality pro- blems caused by insufficient crystallization and excess levels of amorphous material. The energy efficiency of the BKG ® CrystallCut ® system can save more than 3,000,000 EUR in an- nual energy costs for a typical PET resin plant and nearly 200,000 EUR for an extrusion line recycling PET bottle flakes, according to examples based on actual commercial installa- tions. Because the system utilizes residual thermal energy within the material to crystallize pellets from the inside out, it yields an en- hanced crystalline structure that results in lower energy costs for re-melting the mterial. In addition to saving energy costs and preventing amorphous PET clumping, the BKG ® Crystall- Cut ® process yields an almost dust-free product and increases bulk density by eight percent in comparison with a conventio- nal process. Master-Line System with Belt Filter Schematic of CrystallCut Process Nordson Corporation www.nordson.com , www.nordsonpolymerprocessing.com 30 Polymer Processing Extrusion 4/2017