Over decades, a well-known plastics extruder in the Midwest built a solid reputation for delivering high quality, high-performance polymers – which in turn – allowed its customers to produce products on time and on budget. The company’s reputation is based not only on a proven track record, but in making sound investments in plant operations, such as the decision to overhaul its process cooling system when the time was right.
By replacing chillers nearing their end of life with chillers from Chase Cooling Systems, the company has kept pace with increased production and a growing list of satisfied customers.
To keep pace with continued growth and eliminate maintenance issues with existing chillers nearing their end of life, a plastics extruder in the Midwest upgraded its central chiller plant with chillers from Chase Cooling Systems.
A Leader in High-performance Polymers
At the company’s production plant employees manufacture a complete range of engineered, high-performance polymers. At the heart of the operation are numerous extrusion lines and related equipment that operate 24 hours a day, five days per week to produce and ship as much as five million pounds of high-performance polymer pellets each month.
The process of producing pellets begins when the rotating screw on each extruder accepts a carefully calibrated mix of thermoplastic materials, as well as additives, from a hopper and pushes the mixture into the extruder’s barrel. Inside the barrel, material is heated and cooled to the proper melt temperature, which ranges from 400 to 500 oF depending on the materials involved. The screw then forces the material through a die to create a continuous strand of plastic resin, which is then cooled as it travels through a water bath. At the opposite end of the extrusion line, the strands of resin are dried and cut into pellets for shipment.
Cooling Temperatures Vital to Extrusion Process
Chilled water supplied to the extrusion lines is vital to production and product quality goals. Yet the aging central chiller plant was unable to keep pace with demand for chilled water and experienced maintenance issues, which led to plans for a chiller system upgrade.
The original chiller plant system featured four air-cooled chillers used to supply chilled water at 45 oF to the extruders and other production equipment. Three of the original chillers, with a cooling capacity of 30 tons each, were located outside the facility. The system also included a fourth chiller, rated to provide 160 tons of cooling. The fourth unit is a split-system with the evaporator installed inside the plant and the condensing unit, which includes the compressor, condenser, and fans, located outside the building. In all, the original chiller plant system provided approximately 250 tons of cooling capacity.
The chiller system also features a cold- and warm-water tank, each of which has a capacity of 3,000 gallons. The system’s two Variable Speed Drive (VFD) pumps feed warm water from the warm water tank to the chillers at 700 gallons per minute (gpm) and 30 pounds per square inch (psi). The system also includes two separate process pumps to supply chilled water from the cold water tank to production areas at 1,500 gpm and 40 psi.
During production, chilled water cools the barrel of each extruder to keep the melt temperature of base materials and additives at precise temperatures. The melt temperature must be maintained within 10 to 20 degrees to ensure the integrity of the extruded material. Chilled water is also used for each extruder’s water bath.
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