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.
The plant’s goal is to avoid adding any extra heat to the heat sensitive materials as soon as they reach the melt point in the extruder barrel. If the temperature gets outside the targeted melt temperature even a little bit it can start to negatively impact the physical properties of the material. The need to carefully control the melt point places a premium on reliable chilled water.
Growth Outpaces Existing Chiller Capacity
As the plant continued to grow, the need for more chilled water to meet increased production goals outpaced the capacity of the original chillers installed at the plant years ago. Additionally, one or more of the aging 30-ton chillers needed to be taken offline all too frequently for routine maintenance and repairs.
The situation led to scheduling issues with production. As an example, chillers weren’t able to deliver the volume of chilled water at the required temperature during peak production. Additionally the operation experienced unplanned repairs. As a result, the plant need to make adjustments to production, such as slowing the pounds per hour of material extruded – or if that wasn’t possible – shutting down an extrusion line to keep the others operating at the proper melt temperatures.
The aging chillers also became maintenance-intensive, which took time away from a small maintenance staff with other responsibilities. During the warmest summer months, there were also times when a chiller would trip off because it reached its cooling capacity limit.
Knowing it needed to upgrade its central chiller system, the company set out to replace the aging chillers with a solution that would allow it to meet production and quality goals, as well as plans for continued growth.
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CASCO USA Upgrades Plant Chillers
After evaluating a variety of process cooling solutions, the extruder chose to work closely with CASCO USA to upgrade its central plant chiller system with three air-cooled CWB chillers from Chase Cooling Systems. The company has a long-standing relationship with CASCO USA, which is a supplier of process cooling equipment, as well as air compressors and blower and vacuum systems. (See sidebar article about CASCO USA.)
Shown are three Chase Cooling Systems CWB Chillers recently installed at an extrusion plant in the Midwest. Each air-cooled chiller provides 115 tons of cooling.
The team at CASCO USA installed the CWB chillers in 2019 in place of the two aging, 30-ton chillers located outside the production facility. The installation also included new Crane-Deming 350 gpm pumps. The new chillers were installed without the need to replace water tanks, or the need to retrofit piping.
Each CWB chiller at the plant is rated to deliver 115 tons of chilled water for a total of 345 tons of cooling capacity. Each CWB chiller includes a variable speed condenser fan; tandem, hermetic scroll refrigeration compressors; and stainless steel brazed plate evaporators. In addition, each chiller is designed with a microprocessor controller with a user interface that features multi-line display to clearly indicate operating pressures and alarms. The units also use environmentally friendly R-410A refrigerant, which eliminates the use of outdated R-22 refrigerant in the original 30-ton chillers.
To maintain production throughout the upgrade project, the CASCO USA team took the first 30-ton chiller offline and replaced it with one of the new chillers. Later, it shut down the remaining 30-ton chiller and 90-ton chiller and installed the two remaining Chase Chillers.
During normal production today, the three new chillers operate in parallel at 50 to 60 percent capacity each to meet the needs of all eight extrusion lines, as well as other production equipment that includes a 75-horsepower (hp) water-cooled, rotary screw air compressor. The water-cooled air compressor serves as a backup to a newly installed 100-hp air cooled rotary screw air compressor that CASCO USA also supplied and installed. The plant also uses its existing 160-ton split-system chiller as a backup chiller, providing additional redundancy for cooling water if needed.
Customer Relationships, Expertise Fuel CASCO USA’s Success
CASCO USA is a distributor and service provider of air compressors, industrial chillers, pumps, blowers, and vacuum products. Headquartered in Washington, Pennsylvania, about 25 miles south of Pittsburgh, CASCO USA has additional offices in Cleveland, Ohio; Erie, Pennsylvania; Williamsport, Pennsylvania; and Detroit, Michigan. The offices serve customers across Michigan, Ohio, West Virginia, Pennsylvania, and southern New York.
The team at CASCO USA offers air compressors, industrial chillers, pumps, blowers, and vacuum products, along with strong technical expertise and quality service.
Focusing on Optimal Production, Growth
The installation of the new chiller system went smoothly and allowed the plastics extruder to maintain production at all times – and all issues with chiller maintenance are ancient history. Most importantly, the upgraded central chiller system provides more than enough cooling capacity. As such, the company is able to focus on meeting production goals – and not on adapting its production schedule based on the limitations of the original chiller system.
All photos courtesy of CASCO USA.
To read similar plastics industry articles, visit https://coolingbestpractices.com/industries/plastics-and-rubber.