New process-water filtration system substantially reduces power usage in underwater pelletizing

15-Jul-14

An innovative design for the system that removes dirt and fine particles from process water in underwater pelletizing drastically reduces power usage in water filtration and cuts overall pelletizer energy consumption by nearly 10 to 17%, it was announced by Nordson BKG. The Optigon™ water filtration system eliminates need for a separate fines-removal sieve, which in standard systems requires a secondary, dedicated water pump. Instead, all filtration is provided by a Polygon™ drum filter, whose 70-micron screens are finer than the 150-micron 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. By eliminating the secondary pump, the Optigon water filtration system uses only 1,440 KW per year (measured at 8,000 hours), as against 44,000 kW and 98,480 kW for the company’s Opti-Line™ and Poly-Line™ systems, respectively. Since water filtration typically accounts for 10 to 17% of the energy consumption in underwater pelletizing, the energy efficiency of the Optigon system means that overall consumption is cut by nearly that much. “The Optigon system drastically reduces power consumption for process water filtration by, in effect, letting gravity do the work once done by a separate pump,” said Adam Cowart, global product manager for Nordson BKG. “This innovation is part of Nordson BKG’s program of continuous improvement to reduce environmental impact and increase energy efficiency.” Other energy-saving measures developed by Nordson BKG are two that are available to customers as optional features: 1) complete insulation of the water system to prevent loss of heat to the workplace and serve as touch-protection for workers; and 2) insulation of the die plate heating flanges, ensuring a uniform temperature profile in the flow channels and retention of heat in the die plate, with energy savings of 30% compared with standard die plates. “Motors used in our pelletizing systems already achieve the IE2 classification, which is designated as ‘High Efficiency,’” said Mr. Cowart. “Nordson BKG intends to increase energy efficiency to the IE3, or ‘Premium Energy,’ classification in the near future.”