Owens Corning fiberglass sheet process
Owens Corning manufactures building materials systems and composite solutions, with a corporate commitment to sustainability. It produces high quality, long-lasting products — while taking measures to conserve natural resources and minimize its process impact. Owens Corning reduces its carbon footprint by incorporating recycled content, conserving natural resources and reducing greenhouse gas emissions. As part of a company-wide effort to reduce energy costs, Owens Corning’s Guelph Glass Plant installed real-time metering equipment to measure and monitor energy use for its major manufacturing processes. Energy-intensive blowers, fans, pumps and compressors are required to move, heat and cool the tons of molten glass used to produce glass fibers. The 400,000 sq.-ft. facility in Guelph, Ontario, produces tens of thousands of tons of glass fiber annually to make products such as interior car-door panels, ladder rails, bath tubs and windmill blades. The process begins by melting raw sand into molten glass at a temperature greater than 2,500°F. The molten glass is extruded into thin strands like fishing line, which are cooled quickly by a fine water mist and cooling air. Sizing is applied to the cooled strands, which are then wound onto spools or ‘cakes,’ and are dried and cured in ovens.
The dried cakes are fed into the chop strand mat line where they’re chopped into 2-in. to 3-in. long strands. These glass fibers are distributed onto a moving conveyor, where a thermoset resin binder and water are added. The product then goes through a three-zone oven that cures the binder to form an integral web, and the sheet of mat material is wound into rolls. Since 2007, the Guelph plant has invested nearly $344,000 in energy conservation projects as part of a multi-million dollar investment in energy efficiency at Owens Corning operations around the world. The investment in 10 energy-efficiency projects at the Guelph plant reduces electricity consumption by more than 2.3 gigawatt-hours annually and saves more than US$150,000 a year.
One of the challenges for the Guelph site was to find ways to reduce the energy costs of the fans on the critical cooling section of the chop strand mat line. Owens Corning aimed to reduce the speed of the 125-hp cooling fan, and of the three 40-hp recirculation fans on the oven, while not affecting product integrity.
Improper cooling can reduce the tensile strength of the web and cause it to break as it’s being wound into rolls. Using real-time metering equipment, the plant engineers evaluated the potential savings of installing variable speed drives (VFDs) on the fans, and verified that reduced fan speed wouldn’t affect product volume and quality.
“Real-time metering lets you know where you use energy,” says Frank Peel, Owen Corning’s Electrical Engineering Specialist. “And if you make changes you can see where the paybacks are. You don’t know what you’re losing unless you measure it.”
Measurement also was essential to determine the potential return on investment required to apply for the Ontario Power Authority’s Electricity Retrofit Incentive Program (ERIP). The ERIP promotes hydro conservation and management by focusing on improvements in lighting, motors, heating, ventilation, air conditioning (HVAC) and overall electrical systems. Owens Corning’s corporate energy leader approves energy reduction projects based on the best dollar per-kilowatt savings and a maximum three-year simple payback. Getting an ERIP rebate can make the difference in getting a project approved. By using VFDs, this project aimed to reduce the fan speeds to 80% to achieve a 50% energy savings, with return on investment in less than one year.
Another challenge was to install drives compatible with the Guelph plant’s existing control system and communication networks.
“Many drive brands support networks like DeviceNet,” says Peel. “But they typically lack the flexibility to easily map specific data like motor kilowatts, bus voltage and fault code. It usually requires explicit messaging in the PLC code, which tends to be complicated.”
Owens Corning’s Guelph plant engineers turned to its partner of more than 30 years, automation solution provider Rockwell Automation and its local Westburne Ruddy drives specialist. They recommended Allen-Bradley PowerFlex 7-Class AC drives for motor controls that integrate with the existing Allen-Bradley PLC-5 programmable automation controllers and remote I/O and Flex I/O at the plant. Owens Corning found that using Allen-Bradley drives to support the remote I/O is simpler and more cost-effective than adding a new network to communicate to another brand of drive.