HDPE Cooling Towers Take the Heat
Patriot Forge Co. (Ontario, Canada) depends on advanced high-density polyethylene (HDPE) cooling towers to maintain optimum bath temperatures for quenching metal forgings and cooling hydraulic systems.
The forging industry has achieved an impressive place in the North American industrial economy by producing components with unique benefits that are difficult to duplicate by any other metalworking process. As is well-known to all in this industry, forging produces parts that feature excellent fracture toughness, ductility, and both impact and fatigue strength. However, delivering on those attributes also requires dealing with the extremely high heat generated during the forging process, which can reach up to 1150˚C (2102˚F).
Patriot Forge is a supplier of custom open-die and rolled-ring forgings ranging from 5-100,000 pounds in carbon and alloy steels, stainless steel, nickel-based alloys and aluminum. Controlling the high temperatures needed to process these materials is critical to the company’s operation.
Frequently used for industrial applications such as refineries, metal foundries and manufacturing plants, cooling towers are known, generally, for their ability to expel “waste” heat from an industrial process application. Cooling towers achieve this function by evaporating a small portion of the recirculating water, which results in significant cooling of the water returning to the process.
Unfortunately for forging and other industrial processes, the most common type of cooling tower is constructed of galvanized steel. Consequently, it is susceptible to corrosion and rust problems that require ongoing maintenance, often causing expensive process downtime along with repair costs.
To combat the slow, inevitable deterioration, plant personnel are often tasked with patching panels and holes. This work only increases before the cooling tower is eventually replaced. Even with diligent maintenance practices and cooling water chemistries, galvanized cooling towers typically must be replaced every 7-12 years.
As a result, many operations are turning to engineered plastic, HDPE (high-density polyethylene) cooling towers that are impervious to corrosion, require little maintenance and provide a much longer service life – even coming with warranties that can reach 20 years.
Needing an Advanced Solution
With plants in Brantford and Paris, Ontario, Patriot Forge manufactures products for demanding industries such as power generation, petrochemical, heavy equipment, military and aerospace that require consistent quality, including the vital hardness characteristics of forgings ranging from 5 pounds to 50 tons.
According to Derek Hynes, senior mechanical engineer at Patriot Forge, three years ago the company decided to begin the process of replacing its aging, multi-use cooling tower, located at Building One of its Brantford plant.
“The tower we were replacing was a traditional steel model that was rotting out,” Hynes said. “Also, metal models tend to rust and corrode, which usually leads to plugging the water flow – and that can interfere with cooling capacity.”
This cooling tower is used to expel heat from the Building One quench system, a 42,000-gallon water tank into which parts are submerged in water or polymer baths to achieve the desired hardness.
Hynes and his team took the time to investigate what other cooling-tower design options were available that could provide reliable, trouble-free operation for a longer period. The team ultimately chose a cooling tower constructed of HDPE manufactured by Delta Cooling Towers in Philippi, W.V., the company that originally developed the engineered plastic technology. In addition to being unaffected by corrosive environments, HDPE cooling towers require lower amounts of expensive water-treatment chemicals and less downtime for repair or replacement. The company offers models with energy-saving features such as direct-drive fan motors that can reduce electricity costs.
“We saw that this was a polymer-based tower that was UV-protected and included a 20-year warranty, so we were convinced that it would offer long-term dependable service,” Hynes said.
Supporting Multiple Systems
After the initial HDPE tower was successfully installed and exceeded expectations, Patriot Forge decided to acquire a second HDPE cooling tower to support hydraulic cooling for its new 5,000-ton hydraulic press, rail-bound manipulator and hydraulic ring roller.
“This new tower needed to support multiple systems within Building One,” Hynes said. “This included cooling the water that flowed through a heat exchanger used to draw heat off the hydraulic systems of three large pieces of production equipment, including the 5,000-ton press that plays a primary role in the forging processes of the plant. Essentially, all three machines are cycling the water that flows through their hot hydraulic heat exchangers and then through this cooling tower. This enables us to keep the hydraulic fluids at a stable 110˚F.”
Extending the Benefits
Earlier this year, Patriot Forge acquired an additional twin-cell HDPE cooling tower to help cool the quench tanks that are part of the company’s heat-treat system in Building Two.
“Both of the quench tanks are 105,000 gallons, and we use the cooling towers to help maintain a heat level of approximately 100˚F,” Hynes said.
The cooling towers that Patriot Forge selected for this building were the same design as the one selected as a replacement in Building One, Delta’s TM Series induced draft models.
One of the unique benefits of the TM Series is the ability to configure them in combination of up to six units with cooling capacity from 250-2,500 cooling tons. This modular design gives companies the opportunity to conveniently add cooling towers as their processing grows. The new cooling towers installed at Building Two are installed in a two-cell configuration with combined cooling capacity of 836 cooling tons.
“We decided on this size and configuration because the quench tanks in Building Two are much larger,” Hynes said. “So, there is a lot more water you have to process through the towers.”
He noted that installation of the factory-assembled cooling towers was relatively easy. “The HDPE plastic towers are lighter, so we were able to use a smaller crane to install them, which was much more convenient than having to deal with larger, bulkier cranes.”
Hynes said the towers feature vibration sensors on all fans. This eliminates the need to climb the towers to check out the operating performance of the fans, a benefit that Hynes feels is particularly appealing because one of the towers tops out at a daunting 65 feet – “a long way up.”
Delta Cooling Towers, Inc. is headquartered in Roxbury Township, N.J., but manufactures in Philippi, W.V. For more information, contact Delta Cooling Towers, Inc.; 800-289.3358; email: firstname.lastname@example.org; or visit www.deltacooling.com.